Interviews with HKSTPC CEO Mr. Allen Ma and
HKUST Dean of Science Prof. Nancy Ip
香港科技園行政總裁馬錦星先生及
香港科技大學理學院院長葉玉如教授專訪
Nature’s Natural Tear Gas
洋蔥 – 自然催淚劑
Does Stress Turn Hair Grey?
壓力會令人頭髮變白嗎？
Contents
Science Focus 科言
Issue 003, 2014
What’s Happening in Hong Kong? 香港科技活動
Café Scientifique 1
科學咖啡館系列 Google Science Fair Google 科學競賽
Global Education 環球教育
Guide to University Applications in the US 2 申請美國大學指南針 Science Today今日科學 Patient Zero 6 指示病例：伊波拉 Where is Xenon? 8 氙到底在哪裏？
Ocean Acidification Enhances 10
Global Temperature Rise 海洋酸化提高全球氣溫
Amusing World of Science科學趣事
Nature’s Natural Tear Gas 12
洋蔥 – 自然催淚劑
Why do Fingers Wrinkle in Moisture? 14 爲什麽手指浸水後會皺？
Does Stress Turn Hair Grey? 16
壓力會令人頭髮變白嗎？
Who’s Who? 科學巨人
Neuroscience Pioneer: Prof. Nancy Ip 18 神經科學先鋒：葉玉如教授
Spirit and Attitude: Allen Ma, CEO HKSTPC 20 心態 – 主宰你的命運：馬錦星，香港科技園行政總裁
Test Yourself! 22
測一測
Acknowledgements 特別致謝
Copyright © 2014 HKUST Email: [email protected] Homepage: http://sciencefocus.ust.hk Scientific Advisors 科學顧問
Prof Karen Chan 陳潔瑜教授 Prof Simon Chan 陳雲教授 Prof Tom Cheung 張曉東教授 Prof Daniel Lee 李康善教授
Editor-in-Chief 主編輯
Prof. Yung Hou Wong 王殷厚教授
Managing Editor 總編輯
Jing Zhao 趙婧
Student Editorial Board 學生編委 Editors 編輯
Sunjung Lim 林宣廷 Flora Ng 吳紫瑜 Yi Qi 戚益
Wai Lam Raphaella So 蘇韋霖 Oi Ying Wong 黃靄盈
Reporter 記者
Kwan Shu Tse 謝鈞澍
Graphic Designers 設計師
Magnum Chau 周霢霖 Amanda Sin 冼卓妍
Message from the
Editor-in-Chief
主編話語
Dear Readers,
I am excited to present to you the third issue of Science Focus. Each issue, we hope to stay current in our articles and bring you the latest and greatest headlines in the limitless world of science. In this issue, we have in store for you some of the critical issues of the world today, such as the recent outbreaks of Ebola in Central Africa and the increasingly worrisome environmental factor plaguing our planet, Ocean Acidification.
I want to take this opportunity to congratulate our Article Submission Competition winner, Chan Hoi Yue (Diocesan Girls’ School), who wrote about the Science of Human Hair. The article will appear in the next issue of Science Focus. Thanks are also due to those who participated in this competition. We really enjoyed reading all of the submissions. As the competition is ongoing, I urge you all to send in your articles and partake in science writing!
Last issue, we asked students to participate in a mailing list lucky draw with a chance to win an Apple iPad Mini. I am thrilled to announce that Zoe Wong is the lucky draw winner – congratulations! If you have not yet joined our mailing list, you can do so by visiting our webpage: http:// sciencefocus.ust.hk/ and clicking Subscribe Now!
Enjoy your Science Focus!
Prof. Yung Hou Wong Editor-in-Chief 親愛的讀者： 我很高興向大家呈獻第三期「科言」。每期我們都爭取將最新， 最矚目的科學頭條帶給各位讀者。在這一期中，我們為大家帶來一 些全球性的重要話題，例如最近在非洲中部爆發的伊波拉病毒和正 在危害我們地球的環境問題─海洋酸化現象等。 我想藉此機會恭喜「科言徵文比賽」獲獎者陳凱瑜（拔萃女書 院），作文內容為人類髮質的科學，作品將會在下期的「科言」登出。 我們非常感謝各位投稿的同學，我們非常享受閱讀所有的作品。比 賽仍然繼續，我希望你們繼續投稿並參與科學寫作！ 上一期，我們邀請學生參與有機會贏取蘋果 iPad Mini 一部 的通訊錄大抽獎，我很高興在此公佈得獎者是黃嘉儀，恭喜你！ 如果你尚未訂閱「科言」的話，就快 到我們 的官方網站http:// sciencefocus.ust.hk/立刻加入吧！ 主編 王殷厚教授 敬上
1
Need a break from school work and studying? Check out the events in store
for you! 想暫時擺脫繁重的學校課業在有趣的科學海洋中遨遊一下嗎？那就來看看
近期都在舉辦些什麼有意思的活動吧！
Café Scientifique
Listen and participate in discussions of current technological advancements while sipping a cup of freshly brewed coffee. World-renowned experts and scientists are invited to communicate face-to-face with the public every first Monday of each month at Café 8, Hong Kong Maritime Museum, Central Ferry Pier 8. Past events include topics on: the plague, life expectancy and human emotions.
Visit the Café Scientifique Facebook page for event updates: https://www.facebook.com/
CafeScientifiqueHongKong or e-mail and subscribe
to them at [email protected].
Google Science Fair
Since 2011, Google has hosted an annual online science competition, available to students aged 13 to 18 from around the globe. The competition
welcomes any experiments under the umbrella of science. More importantly, it is free of charge!
Exciting prizes to be won: the grand prize includes a US$50,000 scholarship funding, a
life-changing 10-day trip to the Galapagos Islands with National Geographic Expeditions and a
US$10,000 grant toward the winner’s school among others. That’s not all. There are 7 other
category prizes to be claimed! Check out their prizes page: https://www.googlesciencefair.
com/en/competition/prizes
Get a head start and plan your submission now! To get the latest updates for Google
Science Fair 2015, you can subscribe to their mailing list at https://services.google.com/fb/
forms/sciencefairen. 科學咖啡館系列 一邊聽著科學家講解當前的科學，一邊喝著即磨 咖。每月的第一個週一，於中環碼頭8號香港海事博物館 Café 8，「科學咖啡館系列」將會請到世界知名的科學 家和大家一起討論現實科學問題。過去的講座包括：瘟 疫、壽命和人類情緒。 想得知最新消息請即瀏覽「科學咖啡館」Facebook 網站：https://www.facebook.com/CafeScientifique HongKong 或在 [email protected] 留言。 Google 科學競賽 起始于2011年，Google舉辦一年一度的在線科學競 賽提供給世界各地 13歲至18歲的學生。比賽歡迎各種有 關科技學科的實驗，而且參賽費用全免。 是次比賽獎品豐富：大獎得主可贏取50,000美元獎學 金、國家地理贊助的加拉巴格群島十日之旅和10,000美元 資金補助給得獎者的學校等等。此外，Google還準備了 7等獎類別，獎品豐富等著你! 查看獎品網頁：https://www.googlesciencefair. com/en/competition/prizes 取 得 先 機 ， 立 即 策 劃 你 的 項 目 ！ 請於https:// services.google.com/fb/forms/sciencefairen/訂閱 Google科學競賽最新資料。 Useful links 相關網站： 1) https://www.googlesciencefair.com/en/?refresh=postlive (homepage 官方網站) 2) https://www.googlesciencefair.com/en/participants/faqs (FAQ) By Yi Qi 戚益
What’s
Happening
in Hong Kong ?
香港科技活動
Guide to
University
Applications:
United States
申請美國大學指南
By Raphaella So 蘇韋霖Application Systems
Many schools in the United States accept the Common Application, through which students are able to apply to multiple schools using one application form. Some schools that accept the Common App require additional school-specific supplements. Other universities, notably, the University of California (including all 9 UC campuses) use separate application systems.There is no limit to the number of universities students may apply to, but each school charges a separate application fee and applicants should budget accordingly. The average application fee is approximately US$41 (HK$318).
It is recommended to apply to 6 to 8 universities.
招生系統
大部份的美國大學使用中央招生系統「Common Application」。學生可以通過一份Common App表格申 請多所學校。有些使用Common App的學校需要同學遞 交補充表格。加州大學（包括加州大學的九所校園）等其 他學校使用不同的招生系統。 美國大學不限制申請數目，但是每所學校都有申 請費；申請者要作相應的預算。平均申請費用約US$41 （HK$318）。我們建議申請6至8 所大學。3
Decision Plans
Students for ED must apply earlier (usually by November) to get an expedited response from the university (usually by December). The applicant may be admitted, rejected, or deferred for Regular Decision.
Early Decision is binding. Students sign a legal agreement stating that attendance is compulsory, if admitted. Hence, only one application to an ED school is allowed, and simultaneous applications must be withdrawn if accepted into ED.
On the other hand, Early Action is non-binding and can be the decision plan for more than one school. Students may opt to wait for Regular Decision results before deciding which offer to accept. However, some schools offer Single-Choice or Restrictive Early Action instead. Students should check with individual universities for specific details.
Regular decision is advantageous to students who would like to show academic improvement in their first term of F6. Regular Decision is also the perfect opportunity for students to amend their college lists based on ED or EA results, if any.
T h r o u g h o u t t h e a d m i s s i o n p e r i o d , applications are reviewed on a first-come-first-serve basis and spaces become increasingly competitive toward the deadline. Students should apply as soon as possible.
招生計劃
同學提早（通常在十一月）遞交申請表，而大學也會 提早（通常在十二月）回覆。申請者可能被錄取、拒絕、或 延後和Regular Decision的申請者一起考慮。 Early Decision是有約束性的，學生須要簽署一份合 約。若學校決定錄取Early Decision的申請者，該學生一 定要入讀那所學校。因此，學生只能透過ED選報一所大 學，而且一旦被錄取就要立即撤回其他學校的申請。 相反，Early Action不是捆綁式的，所以同學可以等 到Regular Decision的結果出來之後再選擇入讀那一所 大學。同學可以透過 E A 報讀多所學校，但有一些學 校只提供「單選」或「限制式」EA（Single-Choice/ Restrictive Early Action）。同學應該自行向學校查詢 詳情。 Regular Decision的截止日期通常在一月份。第一， 此計劃對希望用中六第一學期成績證明自己有進步 的同學很有利。第二，Regular Decision可以幫助已經 收到EA或ED結果的同學改變選校的好機會。 Rolling Admissions 是先到先得地審閱申請及收 生。也即是說，學位會隨著截止日期迫近而逐漸減少。 因此，同學該儘早報讀這些學校。Please join our mailing list to re
ceive future electronic version s of
Science Foc
us
. Members will be entered into a lucky draw for a chance to win an Apple iP
ad mini! Registration on the
Science Foc
us
homepage!請於網上登記你的電郵
地址，即可參加抽獎，
有機會贏取 Apple iPad mini一部。 立即
在「科言」主頁註冊！
http://scienc
efocus.ust.h
k
Early Decision (ED) / Early Action (EA)
Regular Decision
Choosing Majors
Most students enter university in the United States w ith an undecl a red ma j o r. Wh i l e application systems encourage students to indicate academic interests, students can change their minds upon admission. Nonetheless, some competitive programmes review their candidates separately, so students must declare interest in their application in order to be considered.
Tests
Universities require SAT or ACT scores upon application. Information can be found on their websites at http://sat.collegeboard.org/home and http://www.act.org/products/k-12-act-test/ respectively. Students must check with the university whether they require the writing portion of either test. Most students take the SATs and ACTs in the second term of F5 or the first term of F6. Students may retake these tests during this period, and universities will usually consider the highest scores in each section. Students should research prospective universities for target test scores.In addition, many univer sities requi re international students to take the TOEFL as proof of English proficiency. Their website can be found at http://www.ets.org/toefl. While each institution differs in their accepted TEOFL results, a general score target should be around 79 – 100. TEOFL may be waived if students attend international schools or hold passports of an English-speaking country. Applicants may need to contact the institution for details or waivers.
Students have the option to take SAT Subject Tests and Advanced Placement (AP) Exams. Some universities require two to three SAT Subject Tests. Both SAT Subject Tests and AP Exams demonstrate mastery of particular subjects. Since AP Exams test university-level material, many universities worldwide offer course credits for excellent AP scores.
選科
大部份學生是以「未申報主修」的身份入學的。美國大 學鼓勵同學申報自己的興趣，但還沒確定的同學可以入學 後更改這些決定的。比較有競爭力的科系常常會用不同的 準則收生，要求同學必須在申請表上表達對該科系的興趣 才會被納入考慮。這些科系也可能只透過 Early Decision 或Early Action招生。考試
美國大學會要求申請者完成SAT或是ACT標準測試。 它們的官方網站分別是http://sat.collegeboard.org/ home及http://www.act.org/products/k-12-act- test/。雖然考生可以自選考ACT的寫作卷，但多數大學都 要求寫作的分數。大部份的學生選擇在中五下學期或是中 六上學期應考。同學也可以在這段時間重考，大學通常會 考慮每個部分的最高成績。求學者應調查各所大學的份數 要求。 有些大學要求國際學生考「託福」（TOEFL）以證 明自己的英語水準。想查詢更多，請瀏覽TOEFL官方網 站：http://www.ets.org/toefl。雖然每一間大學的標準 TEOFL成績不同，一般的得分目標應在79-100。若求學者 有英文背景，比如是在國際學校出身或持有英語國家的護 照，大學有可能會免考「託福」。申請者需要聯絡該機構了 解詳細資訊。同學可以選擇考 SAT Subject Tests和Advanced Placement (AP) Exams。有些大學會要求兩到三份SAT Subject Test的成績。SAT Subject Test和AP Exams都 可以展示同學對某科目有深入的了解。由於AP Exams考 的是大學程度，全世界有很多大學會讓成績好的學生換 取學分。
Application Essays
Writing plays a large role in the application process. Students may be asked to compose multiple essays with different prompts. Common e s s a y q u e s t i o n s a re o n t h e a p p l i ca nt’s experiences, reason for wanting to apply or creativity. Essays should be focused on one or two particular experiences and avoid restating their entire transcript or CV.Deadlines
Common App: Please visit the website for 2014-2015 application deadlines. Each University may differ. https://app.commonapp.org/ PublicPages/PublicFile?fn=ReqGrid.pdfUniversity of California: http://admission. universityofcalifornia.edu/how-to-apply/dates-deadlines/
Cost
T h e ave ra g e t u it i o n fo r i nte r nat i o na l students to study at a university in the US is about US$28,500 (HK$220,905) per year. Room and board hikes that up to about US$38,000 (HK$294,813) [http://www.topuniversities.com/ student-info/student-finance/how-much-does-it-cost-study-us].
寫作
寫作是申請美國大學的重要部分。評審員可以透過學 生的文章摸索學生的個性和長處，更準確地判斷學生是 否適合該所大學。題目經常問個人經驗、選讀該學校的理 由、或選擇課程的理由。 在寫個人經驗的時候，同學應當著重一兩個比較特殊 或有代表性的經歷。作文應該避免重複每條成績單或簡 歷上的資料。報名期限
Common App: 每所大學可能有不同的期限，請參 閱Common App網址了解 2014-2015截止申請日期， https://app.commonapp.org/PublicPages/Public File?fn=ReqGrid.pdf 加州大學：http://admission.universityofcalifornia. edu/how-to-apply/dates-deadlines/大學費用
國 際 學 生 在 美 國 大 學 年 均 學 費 約 US$28,50 0 (HK$220,905)。加上食宿達約US$38,000 (HK$294,813) [http://www.topuniversities.com/student-info/ student-finance/how-much-does-it-cost-study-us]。Good
luck!
For the full article with more details, please visit
要閱讀完整版，請參考：
A
resurgence of Ebola Virus Disease in West Africa earlier this year has struck terror within the global community. As of 6 September 2014, the disease has caused 3707 suspected cases, 2106 laboratory confirmed cases and 1848 deaths [1]. The severity of this outbreak marks it as the largest in history, surpassing even the first Zaire ebolavirus (EBOV) outbreak in 1976. EBOV also happens to be responsible for the current outbreak.Ebolaviruses belong to the filoviridae family. Filoviruses cause hemorrhagic fever in humans and other primates. Out of the five ebolavirus species, EBOV is the deadliest strain and has a mortality rate as high as 90% [2]. The virus does not transmit through airborne routes. Instead, it is spread through contact with infected bodily fluids. Patients typically show symptoms and become infectious between 2 to 21 days [1].
In dealing with infectious disease outbreaks, epidemiologists often rush to identify “Patient Zero.” Patient Zero is someone who contracts the virus and introduces it to the human population. By tracking down Patient Zero, epidemiologists are able to map viral transmission, identify those at risk, and prevent further spread of the disease. In addition, Patient Zero is critical in providing information about mutations throughout the virus’ evolutionary history. Genomic data thus allows scientists to develop the most up-to-date treatments and diagnostic tests [3].
To trace Ebola back to Patient Zero, a group of scientists investigated the initial outbreak in
Guéckédou in March. Samples from 20 patients with Ebola - like symptoms were taken and examined for the virus in their blood. The viral genome was then analysed and sequenced, along with any available hospital records. Data from this analysis was able to assist scientists in identifying a 2-year-old as Patient Zero [4]. This child is suspected to have spread the disease to his family and to a health care worker, who then further brought it to neighbouring regions.
In addition, scientists have a theory that fruit bats are potential virus reservoirs for Ebola. This theory is especially plausible as one fruit bat species, Myonycteris torquata, has a large enough population range to cover both Central Africa, the source of EBOV, as well as Guinea, the origin of this current outbreak [5]. However, whether or how an infected fruit bat came into direct contact with Patient Zero remain a mystery. It has been proposed that intermediate hosts such as non-human primates were involved.
No vacci nes o r cu res have unde rgone successful clinical tr ials, but a three - dose treatment of an antibody cocktail called ZMapp administered to Ebola infected monkeys has had promising results. A human clinical trial scheduled to begin in 2015 will provide more information regarding the effectiveness and dosage requirement of ZMapp. Further analysis of the viral genomic data will be required in the characterisation and successful treatment of Ebola Virus Disease.
Patient Zero: Ebola
今
年年頭再次在西非肆虐的伊波拉疫症令全球恐 慌。到九月六日為止，這場疫症已經錄得 3,707 宗懷疑染病 個案、2,016宗實驗室證實個案、和1,848宗死亡個案[1]。這 次史上最嚴重的伊波拉疫情，個案數字已超越了1976年第 一次爆發的薩伊伊波拉病毒（EBOV）案例。兩次的瘟疫恰 巧都是由EBOV造成的。 伊波拉病毒屬於纖維病毒科。纖維病毒可引致人類或是 其他靈長類動物產生體內出血。在五個伊波拉病毒品種當 中，以EBOV所引致的死亡率最高，可達九成[2]。幸好，伊波 拉病毒不能透過空氣傳染。人需要接觸到受感染的體液才 會患病。伊波拉病毒的潛伏期為2至21天。患者開始出現病 徵的時候就有能力感染他人[1]。 為了對抗感染性的瘟疫，流行病學家會致力尋找「指示 病例」。指示病例是指第一個將病毒傳染到其他人的病患 者。找到指示病例後，專家就可以記錄病毒傳染的過程、找 出高危人士、並預防病毒繼續擴散。除此之外，指示病例也 對了解病毒過往的基因突變與進化大有幫助。基因數據能 夠協助科學家研發藥物與診斷測試。 在這次的伊波拉疫情中，一組科學家研究了本年三月在 蓋凱杜的爆發。他們從20位病者取得了樣本，在血液裏尋找 伊波拉病毒，然後測序並分析病毒的基因。他們也翻閱了其 他醫院記錄。從這些數據，他們了解到病毒的進化史，確認 了一名兩歲的兒童為指示病例[4]。這名兒童感染了親人和一 名前線醫務人員。然後這位醫務人員再將病毒傳染到了鄰近 地區 [3]。 科學家猜測果蝠有可能是病毒的原宿主。這個理論有它 的可信度，因為其中一種果蝠，Myonycteris torquata，的 分佈範圍足以覆蓋EBOV的來源地中非，以及這次爆發的源 頭畿內亞[5]。但是，病毒是如何散播到各個地區，那個小孩 如何接觸到有病毒的果蝠仍然是謎。相信也有其他非人的 靈長類動物作為二次宿主參與此過程。 到目前為止，醫學家還未研發出有效的預防疫苗或藥 物，但是有一種混合三種抗體的 ZMapp 療程，在猴子和試 管測試中較有效用。有些患者早期也試用 ZMapp 治療，但 結果含糊 – 醫學家不能確定到底是個人免疫力還是藥物 令患者康復。於2015年開展的臨床試驗將會帶給科學家更 多關於ZMapp的效用和劑量的資料。更多病毒基因的分析 也會有助科學家了解並治療伊波拉疫症。 By Raphaella So 蘇韋霖▲ Courtesy of WHO \ Chris Black © WHO
Nurse Isabel Grovas at the MSF isolation ward in Kampungu comforts a 43-year-old patient who has been diagnosed to have Ebola virus. The village of about 9,000 people is at the centre of the latest Ebola outbreak.
指示病例：伊波拉
References
[1] 2014 Ebola Outbreak in West Africa. Centers for Disease Control and Prevention (September 2014) Retrieved from
http://www.cdc.gov/vhf/ebola/outbreaks/guinea/index.html.
[2] Cullinane, S., Thompson, N. (July 2014). Deadliest outbreak of Ebola virus: What you need to know, CNN. Retrieved from
http://edition.cnn.com/2014/03/27/world/ebola-virus-explainer/
[3] Vogel, G., Genomes reveal start of Ebola outbreak (August 2014). Science Vol. 345 no. 6200 pp. 989-990
[4] Blaize, S. et al., Emergence of Zaire Ebola Virus Disease in Guinea – Preliminary Report (April 2014). The New England Journal of Medicine DOI: 10.1056/NEJMoa1404505 [5] Vogel, G., Are Bats Spreading Ebola Across Sub-Saharan
Xenon
, atomic number 54, is a highly inert noble gas that can be purified from liquid air and is found in the Earth’s atmosphere in trace amounts. It is commercially used in the production of lamps and laser equipments because of its high luminous intensity. Although typically transparent and colourless, xenon will emanate a blue or green colour within a discharge tube. It was first discovered by William Ramsay and Morris W. Travers in 1897 and its name stems from the Greek word for “unknown”.Despite the wide use of xenon in lamp and laser-related industries, the element itself is a scarce resource in comparison to other noble gases. German scientists have found that the Earth’s atmosphere has a far lower content of xenon than the lighter noble gases such as argon and krypton. In addition, the abundance of xenon in the atmosphere is also lower than that in meteorites, which is similar in composition to the formation of rocks on Earth [1]. Several hypotheses exist that attempt to explain the phenomenon of the ‘missing’ noble gas.
It is believed that xenon had not actually ‘escaped’ from the Earth, but is effectively ‘hidden’ somewhere other than the atmosphere, namely glaciers, minerals and the Earth’s core. Scientists suspected that the ‘hiding spot’ is in magnesium silicate perovskite (MgSO3), a major component of
the lower mantle forming the rock layer between the crust and the core of the Earth. They theorised that these rocks may have squirreled xenon from the atmosphere and trapped it within the composition of the rocks. Thus, an experiment was performed in an attempt to replicate this scenario.
Xenon and argon were dissolved in perovskite under conditions of high temperature and pressure to mimic the actual conditions of the Earth’s lower mantle. The results proved disappointing, as argon was successfully dissolved, but xenon was not, indicating that this theory is likely to be untrue.
The results for this experiment gave rise to a different idea and the search for xenon was on. An examination of the Earth’s history revealed that the Earth was struck by meteorites 4 billion years ago, losing much of its primordial atmosphere. Scientists suggested that during the formation of the new atmosphere, noble gases such as argon, which temporarily ‘hid’ in perovskite and were released back into the atmosphere. Meanwhile, poorly-dissolved xenon escaped into space. While difficult to prove, the relative ratio of xenon, argon and krypton in atmosphere content and their individual solubility in rocks correspond, supporting this school of thought [2]. In addition, the fact that the lighter isotopes of xenon is more difficult to find in the atmosphere than the heavier one may also help explain the hypothesis since the lighter isotopes are more likely to escape during the loss of primordial atmosphere than the heavier ones.
Concrete evidence for either of these theories is non-existent and while the latter appears to be a more plausible explanation of Earth’s low xenon levels, there are still many uncertainties. The theory does not address noble gases resulting from radioactive decay from heavier elements such as uranium and plutonium, nor does it consider the logical paradox in the application of the same theory on Mars. More research must be done in order to solve this mind-boggling puzzle.
氙到底在哪裏？
By Yi Qi 戚益This article may be useful for classes learning about “Planet Earth” based on the DSE Chemistry syllabus. 根據 DSE 化學科目，這篇文章有助學習關於 Planet Earth 的課程
氙
是一種惰性氣體元素，在元素週期表上排在第54 位。它的化學性質非常不活躍，不容易與其他分子產生反 應形成化合物，故而在空氣中以單質形式存在，也因此可由 液態空氣分離提純取得。氙因其極高的發光強度而在現代 照明工業中廣泛應用，多用於製造閃光燈管，紫外燈以及 鐳射設備。在常溫常壓條件下，氙呈無色無味的氣體狀態； 但在放電管內卻能呈現出美麗的藍色或是綠色。這種奇妙 的氣體在1897年被科學家拉姆齊（William Ramsay）和 特拉維斯（Morris W. Travers）在分離液態空氣時發現。 其英文名“Xenon”在希臘文裏是“未知”之意。 雖然氙在現代照明工業中有著廣泛的應用，但比起其 他惰性氣體元素，它可算得是一種稀有資源了。德國科學 家發現在地球表面的大氣層中，氙的含量比起其他惰性 氣體（比如氪和氬）要低得多。此外，大氣中的氙含量亦是 低於其在隕石中的含量。隕石的構成成分與地殼岩石頗為 相似[1]。那麼，為何地球表層的氙含量如此之低呢？科學 家為此提供了兩種假說，試圖解釋此現象背後的原因。 第一種假說認為氙並未“逃離”地球，而是藏在冰川、 礦物質或地球的某些角落裏。科學家們認為地球下地幔 （lower mantle）的主要成分矽酸鎂鈣鈦礦（magnesium silicate perovskite MgSO3）可能是“窩藏”氙的地帶。因此，他們試圖複製這種情景，在高溫高壓環境將氙和氬溶 解在矽酸鎂鈣鈦礦中。令人失望的是，實驗結果表明雖然 氬能順利溶解於岩石之中，氙卻是不能。如此一來，這一假 設就基本被推翻了。 這個實驗的結果引起了第二種假說，科學家們轉而回 溯了地球悠長的歷史，終於發現40多億年前，地球曾遭到 許多隕石的撞擊並因此流失了大部分的原始大氣層。於是 他們猜測，在此後的新大氣層形成過程中，那些在岩石中 溶解度較高的惰性氣體（例如氬氣）從岩石中釋放出來；與 此同時，溶解度較低的氙氣逃入了太空。雖然這種說法難 以用實驗證明，但大氣層中氙、氬、氪的成分之比與三者在 岩石中溶解度之比相近，可以作為此假說的有力論據[2]。 另一項重要的旁證是大氣層中較輕的氙同位素相對稀少， 可能是因為在原始大氣流失時，質量較小的較輕同位素更 容易“逃離”地球。 以上假說均缺乏實證，雖然第二種假說似乎較好地解 釋為何氙在地球表層如此稀少，依然有未足之處。這假說 並沒有考慮到放射性元素（例如鈾和鈈）衰變形成的惰性 氣體的影響，也未能解釋在火星上套用這理論時出現的矛 盾。看來，我們離完全揭開地球表層低氙含量之謎還有很 長的路要走。 References
[1] Svyatoslav S., Keppler, H. (October 2012). The origin of the terrestrial noble-gas signature. Nature 490, 531-534 Retrieved from http://www.
nature.com/nature/journal/v490/n7421/full/nature11506.html
[2] Callaway E. (October 2012). The mysterious case of the missing noble gas. Nature News 490. Retrieved from http://www.nature.com/
news/the-mysterious-case-of-the-missing-noble-gas-1.11564
地殼
上地幔
下地幔
外地核
內地核
Do You have feedback or suggestions? Let us know on our website!
你是否有意見或建議 ? 歡迎你在網頁留言
http://sciencefocus.ust.hk
OCEAN ACIDIfication
enhances
GLOBAL temperature rise
compound known as dimethyl sulphide (DMS). DMS oxidises in the atmosphere to form sulphuric acid, which become aerosol particles that ‘seed’ clouds and reflect solar radiation away from the Earth. This process acts as a natural cooling agent for the Earth’s surface [2].
Scientists hypothesised that an increase in global temperatures can promote phytoplankton growth; hence, the production of DMS, and can potentially help offset global warming. Recent research, however, showed that an opposite effect seems more likely. Researchers in Hamburg, Germany numerically modelled the effect of ocean acidification on DMS production and global temperatures. Previous mesocosms studies– enclosed volumes of water – found that DMS production decreases when reducing water pH by 0.3 units, matching the predicted level for 2100, based on a “business as usual scenario”. Under this emission estimation, the heat trapping gases will increase global temperatures by 2.1 to 4.4°C. Assuming that present-day CO2
concentration is doubled (a level much less than what is forecasted by the end of this century), the team predicts an additional 0.23 to 0.48C increase in global temperatures. This prediction highlights a positive feedback between CO2
emission and further temperature increases [3].
Katharina Six from this team cautioned that their research is still in its early stages and much of it is focused on polar and temperate waters. DMS emissions on tropical and subtropical waters have yet to be investigated; dissolution of CO2 is not the same in different regions and
bodies of water. Furthermore, extrapolating data observed in mesocosms over weeks to long-term system dynamics could be problematic. Future
The
Industrial Revolution has brought about positive changes to virtually every aspect of people’s daily lives. However, convenience, increased life expectancy, and improvements in the quality of life have come at the enormous cost of straining the planet’s natural resources. The dramatic increase in carbon dioxide emissions from burning fossil fuels, urbanisation and deforestation, have been identified as leading causes of global warming [1]. Oceanacidification, a process that raises the acidity of surface sea water, due to increased CO2
emission, has recently been identified as a worr ying factor in increasing the average temperature of the planet.
The transfer of gases between the air and the Earth’s water is a process determined by the difference in gas concentration between the two media, and occurs so that an equilibrium can be reached. An increase of atmospheric CO2,
caused by human activities, forces the ocean to take up more CO2. The excess CO2 hydrates
with seawater, which acts as a buffer, and alters the carbonate chemistry through a series of chemical reactions. As a result, protons increase and carbonate ions decrease. These changes in the chemistry of seawater increase acidity and are termed ‘ocean acidification’. Ocean acidification is considered one of the greatest threats to marine ecosystems in the 21st century.
The recent work by the German research group at the Max Planck Institute of Meteorology highlights a double whammy - acceleration of global warming through ocean acidification’s impact on phytoplankton.
Phytoplankton, are tiny photosynthetic organisms, live in the ocean and emit an organic
By Sunjung Lim 林宣廷
comparisons between climate models and further experimental studies are needed to come up with better climate predictions under the influence of increasing human activities [4].
工
業革命確實為人類生活帶來正面的改變，然而種 種便利、壽命延長、以及生活質素的提升，均為地球的天然 資源造成巨大的壓力。以往相信全球暖化，主要是因為燃 燒化石能源釋放大量二氧化碳，加上城市化和過度砍伐林 木[1]。最近，研究人員發現，由二氧化碳排放量增加所引起 的「海洋酸化」過程，可以改變海面水質的酸性，亦有可能 提高地球的平均温度。 空氣和海水包含的氣體濃度若有差異，氣體就會轉移， 直至達到平衡狀態為止。人類的活動造成大氣中的二氧化 碳量增加，海水因而吸收更多的二氧化碳。海水作為酸鹼緩 衝劑，會與過多的二氧化碳合成碳酸，並通過一系列的化學 反應改變其碳酸鹽化學性質，結果是質子增加和碳酸根離 子減少，海水酸度提高，這就是「海洋酸化」。海洋酸化被 認為是21世紀海洋生態系統面臨的最大威脅之一。德國馬 克斯普朗克氣象研究中心近期更指出另一重隱憂：海洋酸 化對浮游植物的影響也會加速全球暖化。 浮游植物是生存在海洋內的微小生物，進行光合作用 並釋放一種名為二甲基硫（DMS）的有機化合物。DMS 會通過氧化反應成為硫酸，以氣膠粒子形態存在於大氣 中，並成為雲凝結核，反射太陽輻射，降低地球表面的 溫度[2]。 以往科學家假設全球溫度上升可以促進浮游植物生 長，因此增加DMS的生產，有機會減輕全球變暖。最近的 研究卻顯示更有可能出現相反的結果。德國漢堡市研究人 員以數值模擬方法，分析海洋酸化對 DMS 生產與全球溫 度的影響。之前對圍隔水體的研究指出，pH值若降低 0.3 單位，DMS 產量將會減低。按常態性預算到 2100 年海水 的pH值就會達至這水平，屆時溫室氣體排放將會令全球 溫度上升攝氏2.1至4.4度。假設目前的二氧化碳濃度翻倍 （已低於世紀末二氧化碳量的預期值），研究小組估計海 洋酸化對 DMS的影響，將會引致温度額外提升攝氏0.23 至0.48度。這項預測強調二氧化碳排放量與溫度升高，是 可以構成正反饋效應[3]。 組員 Katharina Six 說明研究還在初步階段，主要集 中在極地和溫帶水域，熱帶和亞熱帶水域的 DMS 排放調 研還未曾進行；二氧化碳在不同地區和水體的溶解情況不 盡相同。此外，將圍隔水域觀察數週得出的數據，套用在描 述長期系統動態，是存在許多問題。必須要對不同的氣候 模型多作比較，以及進行更多的實驗研究，才能更準確的 預測受人類活動影響的氣候變化[4]。海洋酸化提高全球氣溫
References[1] T. F., D. Qin, G.-K. Plattner, M. Tignor, S. K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P. M. Midgley (2013). Climate Change 2013: The Physical Science Basis. IPCC, Summary for Policymakers. Retrieved from http://www.climatechange2013.org/images/report/
WG1AR5_SPM_FINAL.pdf
[2] Barford, E. (2013, August 25). Rising Ocean Acidity will Exacerbate Global Warming. Nature. Retrieved from http://www.nature.com/
news/rising-ocean-acidity-will-exacerbate-global-warming-1.13602
[3] Kirby, A. (2013, August 26). Acid seas ‘may worsen global warming’. Climate News Network. Retrieved July 25, 2014, from http://www.
climatenewsnetwork.net/2013/08/acid-seas-may-worsen-global-warming/
[4] Six, K., Kloster, S., Ilyina, T., Archer, S., Zhang K., Maier-Reimer, E. (2012, September 18). Global Warming Amplified by Reduced Sulphur
This article may be useful for classes learning about “Energy, Weather and Air Quality” based on the DSE Integrated Science syllabus 根據 DSE 綜合科學科目，這篇文章有助學習關於 「能源天氣和空氣質量」的課程
Onions
are a kitchen staple and form the basis of diverse cuisines. In addition to enhancing tastes, they are rich sources of vitamin C, B6, potassium and dietary fibre [1]. They are frequently used in a variety of Chinese dishes, functioning as grease soakers and subtle sweeteners. However, there is a notorious side-effect while cooking with this healthy and versatile vegetable – the juice contained in onions released during preparation, somehow triggers tears.Basal tea rs a re continuously produced throughout the day to protect our eyes and eyelids, keeping them moist and lubricated. Finally, reflex tears, regulated by the lachrymal glands located above the eyelids, help to wash out irritants, such as dust or smoke [2].
Onion juice contains chemicals that are irritating to the eyes and generate reflex tears in order to flush away the unpleasantness. But how do onions synthesize these chemicals that no
one cares for? To answer this question, we need to trace back to the soil in which onions are grown in. The growth process of onions involves absorbing sulphur from the soil and converting it into organic compounds named amino acid sulphoxides. It is these sulphur-containing organic compounds which lend onions their uniquely pungent odour and flavour.
The gaseous chemical originating from oils of onions is responsible for the tears and is called propanethiol S-oxide. This chemical is a type of lachrymator (tear gas), and triggers the lachrymal glands (tear glands) when it comes in contact with the cornea. Other common lachrymatory agents include pepper spray and phenacyl chloride, used in riot control. Tears are produced in an effort to dilute the irritant. Propanethial S-oxide is also very reactive, and even a small amount will readily react with tears to form sulphuric acid, which produces further burning and stinging sensations [3].
For a long time, it was presumed that alliinase, a crucial enzyme rendered during the process of synthesising onion flavour, was the only enzyme required to produce propanethiol S-oxide. In 2002, a group of Japanese scientists discovered the actual enzyme accountable for the production of propanethiol S-oxide and subsequently named it lachrymatory-factor synthase. This opens up the possibility for onions to be genetically modified without lachrymatory-factor synthase. In fact, the inhibition of lachrymatory-factor synthase not only stops the production of the unwanted irritant, but also increases the production of thiosulphinates, which retain the flavour and odour of onions [4].
By Sunjung Lim 林宣廷
N
a
t
u
r
e’s
Nat
ura
l
Te
ar G
a
s
洋蔥
–自然
催
淚劑
Tears are evoked by
three main causes. The most
familiar type, emotional tears,
flow when we are sad, physically
in pain, distressed or moved from
T h e g e n e r e s p o n s i b l e f o r p r o d u c i n g lachr ymator y-factor synthase was isolated and supp ressed to i nh i bit the en z yme [5 ]. These genetically modified onions resemble natural onions in both shape and taste, but co m m e rci a l i sat i o n of GMO s i s s t i l l h i g h l y controversial, such that tear-free onions have yet to debut in our grocery stores. In the meantime, perhaps an easier method to prevent tearing would be to heat up the onion prior to dicing, so that the enzyme denatures before the formation of propanethiol S-oxide is possible. Or, better yet, get someone else to slice the onion!
N
a
t
u
r
e’s
Nat
ura
l
Te
ar G
a
s
洋蔥
–自然
催
淚劑
洋
蔥是多種令人垂涎之菜式的重要配料，無論是在 家庭廚房還是頂級餐廳裏，都能找到它的蹤影。除了令菜式 的味道更有層次感之外，洋蔥更含有豐富有益的維他命C、 B6、鉀以及膳食纖維[1]。它在中式料理中有解油膩和加甜 的作用。然而，這種健康多功能蔬菜卻有著一個廣為人知的 問題：準備過程中流出的洋蔥汁液會使人淚流不止。 此外，我們全日無間地分泌出基底眼淚，使眼睛和眼臉 保持濕潤以作保護。位於眼簾上方的淚腺則會反射性流淚 以沖走塵埃之類的刺激物[2]。我們流淚的主要原因有三。
最為人熟悉的是因動情而流淚，
我們在憂傷、疼痛、痛苦和
狂喜時，均會流淚。
洋蔥汁含有刺激性化合物，當眼睛接觸到這些化合物時 便會反射性流淚並沖走這些刺激物。但為何洋蔥會製造這種 化合物？要回答這些問題，我們便要看看洋蔥生長的土壤。 洋蔥在生長過程中，會從泥土吸收硫，並將之轉化為一種名 為亞碸氨基酸的有機化合物。正是這種含硫的有機化合物， 使洋蔥擁有其獨一無二的味道。 洋蔥汁內引致我們流淚的氣體稱為丙硫醛-S-氧化物。 這是一種催淚劑，與眼角膜接觸時會誘發淚腺分泌眼淚。其 餘常見的催淚劑有胡椒噴霧和2-氯苯乙酮，兩者均會在鎮壓 過程中使用。在受到刺激後，淚腺製造淚水以作稀釋作用。 丙硫醛-S-氧化物是一種活性相當高的化合物，即使少量已 足與眼淚進行快速的化學作用產生硫酸，因而引起更多灼 熱、刺痛的感覺 [3] 。 長久以來，人們一直認為有一種在洋蔥合成其味道時出 現的的酶，名為蒜氨酸酶，是製造丙硫醛-S-氧化物反應中唯 一需要的酶。在零二年，日本的一個科學家團隊發現了真正 與這化學反應有關的酶，並命名為催淚因子合成酶。從此打 開契機，可以對洋蔥進行基因改造，使其不含催淚因子合成 酶。事實上，抑制洋蔥製造催淚因子合成酶不單能消去洋蔥 的刺激感，更能促進硫代有機物的形成，保留洋蔥的味道， 可謂一舉兩得 [4] 。 相關的基因已經被分離及抑制，使其不再製造催淚因子 合成酶[5]。儘管不催淚的洋蔥在外形和味道上都和普通洋 蔥無異，但由於基因改造食物的商品化仍存在不少爭議，不 催淚的洋蔥何時開售仍未有定案。在市場上未有不催淚的洋 蔥時，我們要避免流淚，可以在剖開洋蔥前，先煮一煮讓製 造丙硫醛-S-氧化物的酶失去作用，要不然就找位朋友幫幫 忙吧！隨著科技的快速發展，
Crop & Food Corporation of New Zealand
和
House Food Corporation of Japan
已經合作培植出不催淚的洋蔥。
References
[1] McGill Blogs (2012, November 6) Why do onions make you cry? Retrieved from http://blogs.mcgill.ca/oss/2012/11/06/
why-do-onions-make-you-cry/
[2] The Human Eye (2009) retrieved from Encyclopaedia Britannica 2006 Ultimate Reference Suite DVD.
[3] Burnham, Paul M., Propanethial S-Oxide: The lachrymatory factor in onions. Hillsborough College, Sheffield, UK. Retrieved from http://www.chm.bris.ac.uk/motm/pso/psov.htm.
[4] S. Imai, N. Tsuge, M. Tomotake, Y. Nagatome, H. Sawada, T. Nagata & H. Kumagai (2002, October 17). Plant biochemistry: An onion enzyme that makes the eyes water, Nature 419, 685.
[5] Aldridge, S. (2008). Tear-free onions. Nature Biotechnology 26, 365.
With rapid advancements
in technology, tear free onions have
already been developed with the
collaboration between Crop & Food
Corporation of New Zealand and
House Food Corporation of Japan.
Swimming
on a hot summer’s day is no doubt a refreshing activity. After soaking in the water for half an hour, however, you might notice that the tips of your fingers and toes become shrivelled and wrinkled, much like a prune. Long showers and baths seem to invite a similar occurrence. Why do we get ‘pruney’ fingers after lengthy exposure to water and what biological purpose does it serve?A previous school of thought suggested that the main cause of skin wrinkling on fingers and toes was the result of ‘osmotic swelling’ of the outermost layer of skin (also known as the stratum corneum). As the name suggests, this is where water moves from a low solute concentration to a high solute concentration through the wall of a living cell. On the contrary, evidence suggests that
wrinkling does not occur in the denervated areas of the digits [1-2]. A similar result is observed when nerves are severed [3].
Current studies have suggested that finger-wrinkling caused by cold moisture exposure is due to digit pulp vasoconstriction, or the narrowing of the blood vessels. This mechanism is controlled by the autonomic nervous system, part of the peripheral nervous system that is responsible for the control of important functions such as heart rate, digestion and respiration. As a result, the fingertip sees a reduction in volume, leading to the ridge-shaped patterns on the tips of fingers and toes [3]. However, finger-wrinkling still ensues in warm water when vasoconstriction does not occur. Moreover, what is the biological purpose of this mysterious mechanism?
fingers
wrinkle
in
MOISTURE
By Oi Ying Wong 黃靄盈為什麼手指
浸水後
會皺?
Why
DO
Recent published papers suggest that finger-wrinkling plays a role in assisting us with gripping objects. Much like the texture of rain treads or tires, the grooves resulting from immersed fingertips provide better grip and higher friction in wet conditions. The gaps act as drainage networks for directing extra moisture away from the surface [2].
To test this hypothesis, twenty participants in the age range of 21 – 34 were asked to manipulate a total of 45 objects from one container to another with dry fingers, once with the objects submerged and once when they were dry. The subjects were then asked to immerse their hands in 40 °C tap water for 30 minutes and repeat the object transfer experiment in both scenarios. In each case, scientists measured and compared the time it took to transfer all objects. The results showed that moisture-induced wrinkled fingers were more efficient in transferring submerged objects than fingers that were not soaked. However, there was no difference in transfer time in manipulating dry objects with or without wrinkled fingers [3].
The results certainly support the theory that wrinkled fingers provide better grip. Practically, perhaps this provided our ancestors with an easier time gathering or collecting food in rivers or in wet weather. Similarly, wrinkled toes may have been able to provide superior footing for our ancestors during wet conditions. While this speculation seems to help explain the peculiar biological reaction, it does not address why digits are not constantly wrinkled. It is postulated that individuals having wrinkled fingers will result in a reduction in fingertip sensitivity and an increase in skin vulnerability. Thus, wrinkled fingers are not evolutionarily preserved because the risks of having this feature cannot outweigh its benefits under dry conditions [3].
夏
日炎炎，最涼快的活動當然是暢泳一番。泡水半 小時後，大家也許會發現手指頭和腳趾都起了皺，這種情 況在平常洗澡時也會發生。同學們有沒有想過其中的原 因和背後的生物意義？ 曾經有學者提出手指頭和腳趾起皺，是皮膚表層（稱 為角質層）滲透膨脹的結果。顧名思義，滲透作用就是水 分會透過細胞膜，從低濃度溶液滲入到高濃度的一方。然 而有證據顯示手指頭沒有神經的部分是不會起皺[1-2]，同 樣情況可見於神經被切斷的個案 [3]。 目前研究指出在冷潮濕情況下手指頭變皺是因為血 管收縮。這過程是由自主神經系統控制，部份外圍神經系 統亦參與調控其他重要的功能，例如心跳、消化系統、呼 吸系統等等。因此，手指頭的體積會減小，引致手指頭和 腳趾出現脊形圖案[3]。可是，手指浸泡在溫水中並不會令 到血管收縮，但手指仍然起皺。這個奧妙的機制有什麼生 物作用呢？ 近期幾份研究論文指出人類手指、腳趾泡水後會起 皺，是讓我們在水裏更容易抓緊物件。手指頭浸水後出現 的坑紋就像雨胎的表面，可以在潮濕情況下提供更好的 抓力和摩擦力，當中的槽就像去水的管道一般，將多餘水 分導走 [2] 。 為了驗證這一假設，科學家邀請了二十位年齡約21 －34歲的參加者，用乾燥的手指拿起45件物體，從一個 器皿送到另一個。其中一次物件是浸泡在水中，另一次物 件是乾燥的。之後，參加者把手指浸泡在40℃的自來水 30分鐘，然後重複實驗。每次實驗後，科學家測量和比較 傳送物件所花的時間。結果顯示，起皺的手指移動潮濕物 件，要比乾燥手指更有效率，但在乾燥的環境中，手指是 否起皺對傳送時間沒有明顯影響 [3]。 實驗結果的確支持了上述的理論，手指起皺現象提供 了更好的抓力，可能讓我們的祖先較輕鬆地在河裏或是 潮濕的天氣中採集食物。同樣地，起皺的腳趾可以令他們 在潮濕的情況下更能抓緊地面。這套說法雖然可以解釋 這種特別的生理作用，但仍然不能解釋手指頭為何不會 老是皺起。可能是因為起皺會減弱手指頭的靈敏度和增 加皮膚的脆弱性，在乾燥環境下遇到的風險高於利益，所 以沒有在進化過程中被保留下來 [3]。 References[1] Yin, J., Gerling, G. J., Chen, X. (2010). Mechanical modeling of a wrinkled fingertip immersed in water. Acta Biomaterialia 6 1487-1496. [2] Changizi, M., Weber R., Kotecha, R., Palazzo, J. (2010). Are wet-induced wrinkled fingers primate rain treads? Brain Behav Evol
77:286-290. Retrieved from http://www.karger.com/Article/Pdf/328223
[3] Kareklas, K., Nettle, D., Smulders, Tom V. (2013). Water-induced finger wrinkles improve handling of wet objects. PMC doi: 10.1098/ rsbl.2012.999
Does Stress Turn Hair
G
RE
Y
?
壓力會令人頭髮變
白
嗎？
It
was said that Marie Antoinette’s hair turned white the night before she was sent to her execution. The event was so peculiar that it was given its own name, the Marie Antoinette Syndrome, used to describe the phenomenon of hair turning white within a short period of time. While many believe that hair greying has a certain degree of correlation with stress, much of the ‘evidence’ is anecdotal and hardly that dramatic. Does stress really whiten hair and was Marie Antoinette’s sudden change of hair colour merely an exaggeration or does it hold a certain amount of truth?Greying or whitening of hair is caused by several factors. An accumulation of hydrogen peroxide, naturally produced by hair cells, is a likely culprit. An excess of hydrogen peroxide blocks the synthesis of a type of pigment called melanin, which gives hair its colour, and is also the determinant of skin colour and the colour of the iris in the eye. Under normal conditions, enzymes
similar to catalase convert hydrogen peroxide into oxygen and water. However, the number of these enzymes decreases with age causing a build-up of hydrogen peroxide and a reduction of melanin
[1]. The same enzymes also enhance tyrosinase
formation, a different type of enz yme that produces melanin in hair follicles. Since melanin is responsible for giving hair its pigmentation, reduction in the number of melanocytes or disruption in the delivery of melanin can turn hair grey or white. The question is, how does stress tie into this?
An experiment involving mice and human scalp yielded some interesting results. Researchers first studied how mice melanocyte stem cells react to ‘stresses’ in the forms of a cut (injury) and exposure to UV radiation. They found that melanocyte stem cells residing in hair follicles near the area of injury migrated toward the skin to produce melanocytes. Some hair follicles in the vicinity of the wound ended up completely void of melanocyte stem cells and new hairs growing out of these follicles were white. Melanocyte stem cells did not completely migrate after mice were exposed to UV and new hairs were still pigmented. In human scalp, researchers removed melanocytes in the samples to see if hair follicle melanocytes would move into the area and a similar effect seemed to occur [2].
Several points should be noted. If any link between physical stress and hair turning white is indicated in this study, it is weak at best. For one, it seems that the movement of melanocyte stem cells from hair follicles to injured skin is dictated by many factors and not injury alone. Second, what people typically associate with hair greying has more to do with mental stress than physical stress such as injuries, as described in this experiment. Thus, it is safe to conclude that to date, no solid evidence exists that links mental stress with hair turning grey.
The question of whether Marie Antoinette’s hair was capable of turning white overnight is perhaps a lot more straightforward to answer. Hair is essentially dead tissue, and does not possess the ability “turn” white; rather, any white hair that appears is grown from the follicle. Since hair takes several weeks to grow, it is quite safe to conclude that the story remains an old wives’ tale – nothing more and nothing less!
傳
說法國皇后瑪麗•安托瓦內特被送上斷頭台的前 一晚，頭髮一夜變白。從此以後，瑪麗的名字就被用來描 述頭髮在短時間內變白的現象。儘管一般相信頭髮花白 與壓力有關，許多所謂“證據”其實是經過渲染的傳聞。 不過壓力是否真能讓頭髮變白？瑪麗•安托瓦內特的頭髮 突然變色又是否反映一定的事實？ 髮絲變白是由許多因素引起，其中最重要的，可能是 髮絲細胞產生的過氧化氫過量積累，阻礙黑色素的形成。 黑色素決定髪色、膚色和眼虹膜的顏色。在正常情況下， 類似過氧化氫酶的酶會將過氧化氫轉變成氧氣和水。但 隨著年齡的增長，這種酶漸漸減少，令到過氧化氫積聚， 黑色素減少[1]。這種酶也會增加酪氨酸酶的形成，酪氨酸 酶能讓毛囊產生黑色素。由於頭髮的顏色是來自黑色素， 黑色素細胞的數量減少或黑色素不能正常輸送，頭髮就 會變白。那麼壓力又是如何影響這種種因素呢？ 從小鼠和人類頭皮實驗得出了有趣的結果。科學家首 先研究損傷和紫外線輻射等壓力，究竟對小鼠的黑色素 幹細胞有什麽影響。他們發現，位於傷口附近的毛囊裏的 黑色素幹細胞，會移動到皮膚產生黑色素細胞。結果是傷 口附近有些毛囊裏沒有黑色素幹細胞，從這些毛囊裏長 出來的是白毛。小鼠被紫外線照射後，黑色素幹細胞卻沒 有完全移走，新長出來的毛仍然帶有色素。在人類頭皮實 驗，研究人員將樣本的黑色素細胞移除，以了解毛囊的黑 色素幹細胞是否會遷移，結果發現相似的現象 [2]。 值得留意的是，即使實驗顯示生理上的壓力與頭髮變 白有關連，證據依然薄弱。首先，損傷之外，還有很多因 素促使黑色素幹細胞由毛囊移動到受傷的皮膚。其次，我 們通常所理解的壓力是精神上的壓力，而不是實驗裏的 生理壓力。所以至今，沒有任何具體證據證明精神壓力可 以令頭髮變白。 瑪麗•安托瓦內特的頭髮是否真的如傳聞所說的一夜 變白？這問題不難回答。頭髮可以看作是死組織，沒有能 力變白。白髮是由毛囊裏直接長出來的。毛髮生長需要數 周，所以結論很簡單，一夜變白髮是不可能的！ References[1] Trüeb, R. M. (2009). Oxidative Stress in Ageing of Hair.
International Journal of Trichology doi: 10.4103/0974-7753.51923 [2] Chou, W. C., Takeo, M., Rabbani, P., Hu, H., Lee, W., Chung, Y. R., Ito, M. (2013). Direct migration of follicular melanocyte stem cells to the epidermis after wounding or UVB irradiation is dependent on Mc1r signaling. Nature Medicine doi: doi:10.1038/nm.3194
Alzheimer’s
disease is an incurable and irreversible neurodegenerative disease, and a form of cognitive dysfunction. There are currently about 35 million people worldwide suffering from Alzheimer’s disease. Every 67 seconds someone in the US develops Alzheimer’s disease. Scientists have been studying the disease since its discovery in 1906 by the German physician Dr. Alois Alzheimer, for whom the disease is named. HKUST’s very own world-renowned neurobiologist, Prof. Nancy Ip, has devoted 30 years into examining the functioning of our brain and the contributing factors of neurodegenerative diseases, such as Alzheimer’s disease.Prof. Nancy Ip was born and raised in Hong Kong. Deeply inspired by her secondary school teachers, she pursued her undergraduate studies in chemistry and biology at Simmons College in Boston. Her passion in research was sparked by her final year project related to the composites of penicillin. After obtaining her bachelor’s degrees, Prof. Ip entered Harvard Medical School and received her PhD degree in Pharmacology. She worked at Regeneron Pharmaceuticals Inc., New York, as a senior staff scientist before joining HKUST in 1993. Currently, she is the Dean of Science, the Morningside Professor of Life Science, the Director of State Key Laboratory of Molecular Neuroscience at HKUST, and Academician of the Chinese Academy of Sciences.
Prof. Ip is well-known for her pioneering research in neurotrophic factors (proteins responsible for growth and maintenance of neurons). By identifying various members of neurotrophic factors and examining their biological mechanisms and functions in neurons, Prof. Ip and her collaborators demonstrated the significance of these proteins in neuronal survival and function. For instance, one of the factors served an important role in facilitating communication between neurons. These findings
神經科學的先鋒 :
葉玉如教授
highlighted a potential role of neurotrophic factors as pharmaceutical agents for neurodegenerative diseases.
P rof. I p cu r re nt l y d evote s h e r t i m e to understanding Alzheimer’s pathology and developing therapeutic interventions. One avenue of work is identifying biomarkers for diagnosing Alzheimer’s disease. Another is leveraging Chinese medicine and modern b i otech no l og y to i dent if y d r ug l ead s fo r neurodegenerative diseases. There is no doubt that empirical knowledge of Chinese medicine has existed for centuries and that it is effective. The biggest challenge is grasping a comprehensive understanding of brain functions. Thus, treating diseases linked to brain dysfunctions is difficult. Prof. Ip’s team however, has recently identified EphA4, a protein found on the surface of brain cells, as a new molecular target for Alzheimer’s disease. Her team has demonstrated EphA4’s involvement in Alzheimer’s pathology, and further identified a naturally occurring compound from a traditional Chinese medicine herb that blocks the activity of EphA4. This discovery marks momentous progress in understanding the underlying causes of and identifying potential therapeutics for Alzheimer’s disease.
Prof. Ip states that “We have investigated only a small piece of a very large puzzle” and is dedicated to making continued contributions to the field towards the betterment of mankind.
阿
兹 海默症 是 一種不能治癒 和不可逆轉 神經 退 行性疾病，也是一種認知障礙症。據估計，目前全球約有 3,5 00萬人患上認知障礙症；而在美國，每 67 秒便產生 一個認知障礙症患者。自 1906 年經德國醫學家愛羅斯• 阿茲海默發現並命名後，科學家便努力不懈地研究阿兹 海默症。香港科技大學（下稱科大）的葉玉如教授，是國際 頂尖神經科學家，在過去三十年致力研究大腦的運作機理 和阿兹海默症等神經退行性疾病的主要成因。 葉玉如教授在香港出生和成長，中學時期深受老師的薰 陶，畢業後負笈波士頓的西蒙斯學院繼續其化學與生物的 本科學業，其畢業論文是關於盤尼西林，由此啓發她對科研 的熱情。之後入讀哈佛醫學院，並獲得藥理學的博士學位。 畢業後在紐約Regeneron製藥公司任職高級科學研究員， 並於 1993 年加入科大。葉教授現任科大理學院院長、晨興 生命科學教授、分子神經科學國家重點實驗室主任和中國 科學院院士。 葉教授是研究｢神經營養因子｣（負責生長和維持神經 元的蛋白）的先驅。透過識別不同類的神經營養因子和探 索它們的生理機制和功能，葉教授與她的合作者們展示了 這些蛋白在神經元存活下的意義。例如：她們發現其中一 個因子的可以促進腦細胞之間的訊息傳遞。這些發現意味 著神經營養因子作為神經退行性疾病藥劑的潛力。 葉教授現時正致力於研究阿兹海默症的病理和發展 治療性干預。其一研究方向包括識別阿兹海默症的生物標 記。另外，其研究團隊利用現代生物技術探索中藥的藥理 機制、以及識別可用於治療神經退行性疾病的先導藥物。 中藥經過了多個世紀的驗證，其功效無可置疑，而最大的 難處是在於要全面了解腦功能的運作。至今科學界尚未能 掌握學習和產生記憶的機理，因此要治療與這些功能失調 有關的疾病是很困難的。不過，葉教授與她的研究小組最 近識別了一種存在於腦細胞表面上的蛋白，名為EphA4， 是阿兹海默症的分子指標。研究人員探討了EphA4在阿兹 海默症的病理角色，並從中藥篩選出一種可以抑制EphA4 活性的天然化合物，在阿茲海默氏症的病因和干預措施的 研究取得突破性進展。 葉教授指出｢我們只是探索了巨幅拼圖中的一小片｣，並 謙虛地表示希望能繼續為創建更美好的未來作出貢獻。By Kwan Shu Tse 謝鈞澍
Prof. Nancy Ip
Neuroscience Pioneer:
Full interview with Prof. Nancy Ip available on our website.
請在我們的網站閱讀完整的採訪。 http://sciencefocus.ust.hk/nancyip
University
has become an integral part of education in Hong Kong and an obvious step after graduating from secondary school. Training to obtain a tertiary education degree begins as early as primary school (and some would argue, even earlier), involving countless hours of private tutoring, all in the hopes of entering a prestigious tertiary institution to secure a brighter future. However, are students entering university with the right mindset and for the right reasons?Allen Ma, Chief Executive Officer of Hong Kong Science and Technology Parks (HKSTPC), offers his take on success.
To him, having the correct attitude and finding the true interest are crucial for university life. That is not to say that knowledge and a deep understanding of the topic are not important, but rather, that the combination of knowledge
and interest is the formula for accomplishing a successful career. “A job or major that you are not happy with equals wasted resources and wasted time”. The discovery of an interest is the first step in attaining a deeper understanding of a subject, which can blossom a mere inception into a fruitful business. Raising Wong Tao (an HKUST alumnus) as an example, Ma mentioned how he turned his interest of model airplanes into a multi-billion dollar empire.
Mr. Ma’s advice is supported by his own story. He graduated with a bachelor’s degree in accounting and holds an MBA degree but had always reserved interest in science and technology. With 30 years of experience in senior executive positions in telecommunications and technology companies, he continues to absorb knowledge from colleagues, experts, professors and from reading related materials. Staying true to his interests and being incredibly successful at the same time, he is currently appointed as the CEO of HKSTPC, hosting 450 companies, 300 of which are large international firms or small business and 150 of which are dedicated to entrepreneurial training.
