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Science Focus by HKUST

🌸A science magazine published by the School of Science at HKUST Science Focus is a science magazine published by the School of Science at HKUST.

Specially written and designed by HKUST science students under the guidance of School of Science faculty and staff, Science Focus is offered free-of-charge to Hong Kong secondary school students, three issues per annum. Email: [email protected]

We welcome your feedback. School of Science affiliate pages:
LIFS Human Genetics Workshop: https://www.facebook.com/humangenetics.hkust/

18/09/2025

《為甚麼蘋果切片會變成棕色？🍎》
Why do sliced apples turn brown?

蘋果切開後，果肉接觸到空氣中的氧氣，會使多酚氧化酶開始催化多酚氧化的過程。這個酶促反應產生鄰醌（o-quinones），其及後與胺基酸結合後，會形成褐色的黑色素（melanins）。

由於不同品種的蘋果所含的酶和多酚多寡不一，所以切開後變黃的速度也不一樣。

蘋果切片後保持新鮮的秘訣：
❄️ 冷藏降溫 → 降低酶活性
🍋 與檸檬汁混合 → 透過降低pH以降低酶活性，並讓檸檬中的抗氧化成分發揮作用！
🍯 愛甜口？裹上一層蜂蜜、焦糖或糖漿 → 隔絕氧氣超有效

When an apple is cut, the apple's flesh is exposed to oxygen, which triggers the oxidation of polyphenols by the enzyme polyphenol oxidase. This enzymatic reaction produces o-quinones, which subsequently react with amino acids to form brown melanins.

Different apple varieties contain varying levels of the enzyme and polyphenols, so they brown at different rates.

To keep apple slices fresh:
❄️ Chill them → reduce enzymatic activity
🍋 Toss them in lemon juice → reduce enzymatic activity by lowering pH, and let the antioxidants of lemon work!
🍯 For a sweeter fix, coat them in honey, caramel, or syrup → physically block oxygen

By .___ (on IG) & Audrey

09/09/2025

✨We’re Recruiting! 📢

Do you want to join our efforts to popularize science?
Or be a future graphic designer or content creator?
…Here comes the chance that you shouldn’t miss! 😃

We are looking for HKUST science undergraduate students to prepare contents for the print magazine and social media pages, under the supervision of staff and faculty from the School of Science.

For details, please refer to the email dated September 9, 2025 (Tue). The application deadline is September 21, 2025 (Sun).

Should you have any enquiries, please direct them to [email protected]. 📧
-----⠀⠀

21/08/2025

《甚麼是無乳糖產品？🧀》
What are lactose-free products?

無乳糖乳製品讓乳糖不耐症人士也能享用乳製品，但到底怎樣才能生產出這些產品？

要生產無乳糖產品，可以先過濾掉牛奶中40%乳糖，再加入乳糖酶把剩餘乳糖分解成身體可吸收的葡萄糖和半乳糖。

某些乳製品本來就含有較少乳糖，因為這種雙糖會在製作過程中被去除，使部分乳糖不耐症人士也能無恙地攝取。例如車打或高達芝士這類硬芝士中的大部分乳糖在製作過程中會隨著乳清排走，而剩餘的乳糖則被乳酸菌分解，因此每100克芝士僅含低於0.05克乳糖 ── 可說是幾乎不含乳糖！

Lactose-free dairy products cater for the need of people with lactose intolerance. How are they made?

To produce lactose-free products, milk can be first filtered to remove around 40% of lactose. Lactase is then added to break down the remaining lactose into glucose and galactose, which can be absorbed by the body.

Certain dairy products are naturally low in lactose as the disaccharide is removed during the manufacturing process. These products can be consumed safely by some people with lactose intolerance. For example, hard cheeses like Cheddar or Gouda have most of their lactose removed along with whey, and the remaining lactose is metabolized by lactic acid bacteria. Therefore, these cheeses have less than 0.05 g lactose per 100 g – practically lactose free!

By .___ (on IG) & Audrey

07/08/2025

《甚麼是乳糖不耐症？🍼》
What is lactose intolerance?

乳糖不耐症患者無法消化乳糖，進而可能在攝取奶類後腹瀉和腹脹。

在理想的情況下，乳糖酶會將乳糖分解為葡萄糖與半乳糖，然後這些單糖經腸道內壁吸收至血液。

乳糖不耐症成因是小腸在成年後無法製造足夠乳糖酶。這是一個常見的情況，因為只有北歐和印度西北部的人保留在成年後消化乳糖的能力。

未被分解的乳糖進入結腸，因水勢緣故將水份從血液抽至腸道，同時腸道細菌能分解乳糖並產生氣體，造成腹瀉和肚痛等不適。

Lactose intolerance is the inability to digest milk sugar, possibly resulting in diarrhea and bloating after dairy consumption.

Ideally, lactase breaks down lactose into glucose and galactose. These monosaccharides are absorbed via the intestinal lining into the blood.

Lactose intolerance occurs when the small intestine doesn't produce enough lactase after reaching adulthood. This is a common condition because only Northern Europeans and Northwestern Indians retain the ability to digest lactose.

The undigested lactose moves to the colon and draws water from the bloodstream due to osmotic pressure. Gas is also produced when the lactose is broken down by gut bacteria. These can cause diarrhea and abdominal pain.

By .___ (on IG) & Audrey

24/07/2025

《隱形眼鏡護理液知多點 👁️》
A Guide to Contact Lens Solutions

隱形眼鏡護理液主要有兩種：雙氧水和多用途溶液。它們的區別在於消毒方式的不同。

雙氧水使用過氧化氫（H2O2）作為消毒劑，濃度通常為 3%。隱形眼鏡盒中的鉑、鈀或銀等催化劑可以加速降解對眼睛有害的過氧化氫，使其分解為水和氧。

多用途溶液通常含有聚己亞甲基鹽酸或聚季銨鹽-1等消毒劑，兩者均能阻礙細菌增長。

其他成分如雙磷酸鹽（bisphosphonates）有助分解鏡片配戴時累積的蛋白質，而保濕與護理化學成分則能確保鏡片在存放期間維持良好狀態。

溫馨提示：潤眼液和隱形眼鏡護理液因成分不同，所以不能把其看待成相同東西交替使用。

There are two main types of contact lens cleaning solutions: peroxide solutions and multi-purpose solutions. They differ by the way they disinfect.

Peroxide solutions utilize hydrogen peroxide (H2O2) as a disinfectant, typically at 3% concentration. The catalyst present in the contact lens case, such as platinum, palladium or silver, can speed up the degradation of harmful peroxide into water and oxygen.

Multi-purpose solutions typically contain disinfectants such as polyhexamethylene biguanide or polyquaternium-1, both of which can inhibit bacterial growth.

Other compounds such as bisphosphonates help break down proteins that accumulate on the lens during wear, while moisturizing and conditioning chemicals ensure good storage conditions.

A final reminder: Eyedrops and contact lens solutions cannot be used interchangeably due to their different compositions.

By .___ (on IG) & Audrey

10/07/2025

《為何咖啡因能驅散睡意？☕》
Why Can Caffeine Ward Off Drowsiness?

咖啡因是一種天然興奮劑，存在於某些植物中，包括咖啡豆、茶葉和可可豆。常見的咖啡因來源包括咖啡、茶、汽水、能量飲料及巧克力。

咖啡因是腺苷的競爭性抑制劑，因此能刺激中樞神經系統。一般來說，腺苷會與其受體結合帶來睡意，但咖啡因正正能透過堵住腺苷受體來阻斷這個過程。

對於健康成年人，美國食品藥物管理局（FDA）指出咖啡因的安全攝取量為每日400毫克，約為兩至三杯「中杯」（tall size）咖啡。過量攝取咖啡因可能導致失眠、焦慮、心跳加速、頭暈和胃部不適等症狀。

Caffeine is a natural stimulant found in certain plants, including coffee beans, tea leaves, and cacao beans. Common sources of caffeine include coffee, tea, soft drinks, energy drinks, and chocolate.

Caffeine stimulates the central nervous system by acting as a competitive inhibitor of adenosine. The binding of adenosine to its receptor promotes drowsiness, but caffeine can halt this process by blocking the receptors.

For healthy adults, the FDA cites 400 milligrams per day as a safe amount, equivalent to about 2–3 “tall” size coffee. Typical symptoms of caffeine overdose include insomnia, anxiety, increased heart rate, dizziness, and upset stomach.

By .___ (on IG) & Audrey

26/06/2025

《佩戴隱形眼鏡小貼士👁》
Hacks for Wearing Contact Lenses

✅ 佩戴隱形眼鏡前應先除去手上水份
解釋：市面上售賣的大多數隱形眼鏡都是親水的，使用乾燥的手能避免鏡片黏在手上。

✅ 在徹底洗淨雙手後，以帶有水份的手取下隱形眼鏡

💡 為甚麼隱形眼鏡是親水的？
現時的隱形眼鏡主要由水凝膠製成，其果凍結構由不溶於水的交聯聚合物網絡組成，由於聚合物含有氧等電負性高的原子，因此能與水形成氫鍵。

故此水凝膠能有效鎖住水分，其吸水能力可達自身重量的85–90%，形成柔軟且富彈性的質地。

✅ Wear contact lenses with a dry hand
Explanation: Since most contact lenses on the market are hydrophilic (water-loving), using a dry hand can prevent the lenses from sticking to your hand.

✅ Use a wet hand to remove contact lenses after washing your hands thoroughly

💡 Why are contact lenses hydrophilic?
Most contact lenses nowadays are made of hydrogel, with a jelly-like structure formed by an insoluble cross-linked polymer network. Due to the highly electronegative atoms such as oxygen in the polymer, the network can form hydrogen bonds with water.

Because of this, hydrogel can trap water effectively. By absorbing as much as 85–90% of water of its own weight, hydrogel is a soft, flexible material.

By .___ (on IG) & Audrey

16/06/2025

第三十期《科言》出版啦！😄

您可以在科大何廷錫伉儷訪客資訊中心或SCI/HOME領取實體版《科言》，亦可瀏覽電子版：https://ebookshelf.ust.hk/flippingbook/G23502/

《科言》是由科大理學院學生參與撰寫及設計的免費科學雜誌，每期會派送到超過130間中學，歡迎中學老師為學生訂閱。

Science Focus (Issue 030) is out! 😆

Printed copies are available at Mr & Mrs Ho Ting S*k Visitor Information Center or SCI/HOME at HKUST campus. E-book can be viewed at https://ebookshelf.ust.hk/flippingbook/G23502/.

Science Focus is a magazine published by the School of Science, HKUST. It is prepared by our undergraduate students and offered free of charge to everyone. We have been delivering our magazine to more than 130 secondary schools. Interested teachers are welcome to subscribe for your school.

22/05/2025

《含羞草🌿》
Mimosa pudica

大家經過草叢時，會特別留意有沒有含羞草嗎？

含羞草（Mimosa pudica）是種豆科植物，眾所周知它被觸碰後小葉會迅速合攏。含羞草小葉底部有一組伸展組織和一組屈曲組織，兩者的屈伸可以控制每對小葉的運動。

物理刺激會使水分由伸展組織流向屈曲組織。失去水分的伸展組織會因變得軟縮而收縮，相反獲得水分的屈曲組織會因變得硬脹而伸長，最終令小葉合攏。

When you walk pass the bushes, would you try to spot Mimosa pudica?

Mimosa pudica is a plant in the pea family, which is known to close its leaflets rapidly in response to touch. The sensitive plant has extensor and flexor cells at the base of the leaflets. The reciprocal contraction and expansion of these groups of cells control the movement of each pair of leaflets.

Mechanical stimuli cause the water to redistribute from the extensor to the flexor. As a result, the extensor becomes flaccid and contracts, whereas the flexor becomes turgid and stretches, resulting in the closure of leaflets.

By .___ (on IG) & Audrey

17/04/2025

《世界上「最醜」的動物：水滴魚 💦》
The World ’s “Ugliest” Animal: The Blobfish

水滴魚必定高踞世上最醜動物排行榜的頭幾位，牠們扁平的身軀和凸出的眼睛，絕對不會符合任何學派對美學的描述。

水滴魚泛指隱棘杜父魚科的成員，牠們住在大西洋、太平洋及印度洋的海底，深度約 600–1200 米，那裡的水壓是大氣壓力的 60–120 倍。

水滴魚是擁有非常少肌肉的一團果凍狀物體。牠們身體幾乎是由水分和脂肪混合而成，因此擁有低於海水的密度，能浮在海床之上。

然而令大家想不到的是，水滴魚在高水壓的生境裡形狀就是正常的一條魚。只是被拉上水面時，周遭急降的壓力才使其身體像氣球般澎漲，漲得完全「不成魚形」。

此外水滴魚是伏撃型捕食者，會狩獵海螺、海蛇尾、海葵，以及其他海床上的底棲生物。在繁殖方面，水滴魚會在岩石上每次產上成千上萬顆卵，即將成為母親的水滴魚們亦會成群保衛巢穴。

Among the world’s ugliest animals, the blobfish will always be ranked near the top. With their squashed flat bodies and bulging eyes, any measurement of beauty would put them into a disadvantaged position.

Blobfish, fishes in the family Psychrolutidae, lives at the bottom of the Atlantic, Pacific and Indian oceans. They live at depths of approximately 600–1200 m underwater, where the pressure is about 60–120 times that of atmospheric pressure.

They are primarily a jelly-like mass with very little muscle. The blobfish is a mass of mostly water and fat, which offers a density less than water's, allowing it to float above the sea floor.

Perhaps it is hard to imagine that blobfish just looks like a regular fish in its usual habitat of high water pressure. Only when it is dragged out of the water, the sudden drop of pressure causes its body to expand into a balloon.

In addition, the blobfish can be an ambush predator when hunting for snails, brittle stars, anemones and other bottom dwellers. As for reproduction, they lay eggs on rocks, thousands at a time, and expectant mothers would guard their nests together.

By .___ (on IG) & Audrey

27/03/2025

《蜜蜂如何製造蜂蜜？🐝》
How do Bees Make Honey?

蜂蜜對蜜蜂而言是一個重要的食物來源，特別是在花朵凋零的冬天。

工蜂使用牠們吸管狀的口器從花朵採集花蜜，並將花蜜儲存在蜜囊中。蜜囊是個與胃分開的結構。酶會被添加到蜜囊裡的花蜜。這些酶會分解糖分，例如將蔗糖轉化為葡萄糖和果糖，使蜂蜜不易結晶，以便長期儲存。

工蜂回到蜂巢，將花蜜反芻到內勤蜜蜂的嘴中。這個過程隨著花蜜在內勤蜜蜂之間傳遞會重複多次，讓更多的酶被添加到花蜜中。

之後花蜜會被存放在蜂巢內六角形的巢室中。蜜蜂拍翼製造氣流，加速花蜜的水分蒸發，使其濃縮成蜂蜜。當蜂蜜的水分含量降到約18％以下，蜂蜜就會濃稠得足以透過滲透作用抽乾細菌和真菌的水份，抑制微生物生長。然後蜜蜂就會封住巢室，保存蜂蜜供未來使用。

Honey serves as a vital food source for bees, especially during winter when flowers are gone.

Worker bees collect nectar from flowers using their long tongues. They store the nectar in their "honey stomach," which is separate from their regular stomach. In the honey stomach, enzymes are added to the nectar. These enzymes break down sugars, such as converting sucrose into glucose and fructose for long-term storage, so that the honey is less prone to crystallization.

The bee returns to the hive and regurgitates the nectar into the mouth of a processor bee. The process is repeated several times when the nectar is further passed on to more processor bees, allowing more enzymes to be added.

Then, the nectar is deposited into hexagonal beeswax cells in the hive. Bees fan their wings to create airflow, which facilitates water evaporation from the nectar, thickening it into honey. When the water content decreases to around 18% or below, the honey becomes so thick that it can draw water through osmosis from bacteria and fungi to inhibit their growth. After that, the bees cap the honeycomb cells to preserve the honey for future use.

Prepared by .___ (on IG) & Audrey

13/03/2025

《「防暈浪眼鏡」及「車輛移動提示」😵‍💫》
Motion Sickness Glasses & Vehicle Motion Cues

動暈症（俗稱「暈浪」）由來自眼睛和身體不匹配的訊息引起，當中眼睛或身體其中一方感受到我們正在移動，另一方卻認為我們靜止不動，使大腦無所適從而產生暈眩和噁心的感覺。

「防暈浪眼鏡」的兩側各有一個額外的圓形邊框，眼鏡的全部四個邊框都是圓形的空心管，裡面有顏色鮮艷的液體，液體在車輛運動時會隨着移動，為眼睛提供與身體感覺匹配的視覺線索。

另一方面，手機中的「車輛移動提示」功能透過在螢幕邊緣顯示與車輛動態同步的黑色小點，在不干擾手機操作的情況下，為手機用家提供車輛移動的視覺線索，預防暈浪。

Motion sickness is caused by the conflicting messages from our eyes and body – one sensing that we are moving whereas another feeling that we are at rest. They confuse our brain and cause dizziness and nausea.

Motion sickness glasses have an additional rim on both left and right. All four rims are circular tubes filled with brightly colored liquid. The movement of the liquid matches that of the vehicle, thus providing visual cues that align with the body’s sensation.

On the other hand, the “Vehicle Motion Cues” feature on your mobile phone are animated dots displayed at the screen edges, which are synchronized with the vehicle's movement. These dots can also prevent motion sickness by offering visual cues that match the vehicle’s movement without disrupting phone activities.

Prepared by .___ (on IG) & Audrey

Address

Office Of The Dean Of Science, The Hong Kong University Of Science And Technology, Clear Water Bay
Kowloon

Website

https://sciencefocus.hkust.edu.hk/

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Science Focus is a science magazine published by the School of Science at HKUST. Specially written and designed by HKUST science undergraduate students under the guidance of our faculty and staff, Science Focus is offered free-of-charge to Hong Kong secondary school students, two to three issues per annum. The aim of the magazine is to stimulate and nurture students’ interest in science and scientific research through interesting articles. Email [email protected] We welcome your feedback. School of Science affiliate page: LIFS Human Genetics Workshop: https://www.facebook.com/humangenetics.hkust/