WYK Biology Club

Science Today #3, brought you by Gregory Tang
Dec 2015
Technology

Transparent metal films

Indium tin oxide (ITO) is a transparent conductor used in 90 percent of the display market. But its price has increased dramatically in the last decade. Usually, the display in mobile devices makes up 40 percent of the cost and is getting more expensive from generation to generation. Today, researches find a class of material, correlated metals, to replace ITO. In correlated metals, like strongtium vanadate and calcium canadate, the electrostatic interaction between electrons is very large comparing to their kinetic energy. Such correlation effect makes the electrons 'feel' each other and act like liquid rather than gas. While being conductive, it also becomes less reflective when you shine light on it, thus more transparent. The advantage is that SrVO3 and CaVO3 cost less than five percent of that of indium. Apart from display technologies, researches are combining their new materials with a promising solar cell that uses organic perovskites, which outperform commercial silion solar cells but require inexpensive transparent conductor. As SrVO3 is also a perovskite, it is possible to make inexpensive, high-efficiency solar cells in the future.

Science Today #2, brought you by Gregory Tang
Dec 2015
Health

Humans evolved to get better sleep in less time

Humans are exceptionally short sleepers, getting on average of seven hours of sleep, whereas other primates, need as many as 14 to 17 hours. What's interesting is that we tend to sleep more efficiently, meaning we spend less time in light stages of sleep and more time in deeper stages. A dream state called Rapid Eye Movement Sleep, makes up 25 percent of our overall sleep. However, it only takes five percent for other primates. Artifical light and other aspects of modern life are not the only factors to this phenomenon. Rather, humans replaced sleep quantity with quality long before the invention of smartphones. Early humans sleep near fire to keep warm and ward off predators. And these habits could enable our ancestors to get the most out of their sleep in the shortest time. Besides, shorter sleep could freed up time to devote to other things, like forging social bonds and learning new skills, while deeper sleep helps to cement the skills, sharpen memories and boost brainpower.

Science Today #1, brought you by Gregory Tang
Dec 2015
Health

Treating colon cancer by vitamin A

Colon cancer is a leading cause of cancer deaths worldwide. When patients recieve chemotherapy, most cancer cells die off. But some stem cells containing genetic mutations that caused cancer could survive and cause a relapse. HOXA5 is a protein which make sure every tissue is correctly identified to maintain the function of different tissues. Some studies show that the cancerous stem cells use a biological mechanism, signaling pathway, to block the HOXA5 gene. Now, researches find that vitamin A, known to induce differentiation of skin stem cells, can re-activate HOXA5. It could be effective against colon cancer, not only for treatment of existing disease but also as a preventive measure. So, let us eat more carrot now!

There will be Frog Dissection activity on 16/11(Mon) after school at Biology Lab.

For those who are interested, please fill in the form which will be distrubuted to each class on Tuesday.

《十一月之蜻》ㄧ 黃蜻 Wandering Glider
學名: Pantala flavescens
蜻科 Libellulidae

遠方的候鳥陸續到訪，又到了立冬的季節。仲夏晚間啁啾的蟲鳴沉寂下來，換上嗖嗖的風聲。這個時候大部份的昆蟲彷彿都躲藏起來，以各種不同的方式度過寒冬。儘管如此，黃蜻就屬於例外。

即使在香港最寒冷的月份，也可見到一小群的黃蜻在飛舞。要是你在冬天看到蜻蜓在風勢較緩慢的地方出沒，那很可能就是牠了。黃蜻就像牠的英文名Wandering Glider所形容的一樣，像一架「漂流滑翔機」，飛行能力高強。牠的遷徙能力亦驚人，從牠另一個英文名Global Skimmer中可以得知，牠的全球分佈是何等廣泛。

黃蜻在民間對預警天氣轉變的智慧中，也佔有一席位。小時候是否曾聽老人家說過，蜻蜓大量出沒低飛時，往往就是壞天氣要來臨的先兆？黃蜻正是當中的主角之一。你是否留意到，颱風來臨前，常見黃蜻漫天飛舞，尋覓體型細小的昆蟲，好等牠們能大快朵頤？這情景正正配合黃蜻的另一英文名Typhoon Dragonfly，意即「颱風蜻蜓」。

下次遇上上述情境時，不妨留意天氣預報，看看自然界的預言是否跟現代科技不謀而合？

參考資源：香港濕地公園

《十月之鳥》ㄧ 林鷸 Wood sandpiper
學名: Tringa glareola
鷸科 Scolopacidae

林鷸是香港常見的春、秋兩季過境遷徙鳥和冬候鳥，牠們以香港作為中途補給站，過境至東南亞和澳洲渡冬，又或直接在香港渡過冬天。在任何有水淹的開闊地區，尤其是淡水濕地，都有可能見到林鷸的影蹤，而除了紅樹林沼澤等鹹淡水濕地外，它們一般不見於海岸。

林鷸是一種涉禽，在香港多數見於水邊，那牠和「林」又有甚麼關係呢？原來林鷸在繁殖期內，確實與森林密切相關。於南方渡冬過後，牠們會於五月至七月中回到歐亞大陸的北部繁殖，當中包括北方針葉林與其內開闊的沼澤地、凍原間的灌叢、多苔蘚或草的沼澤或會在周圍有茂密植被的地上營巢。

辨認林鷸，要留意牠深褐色的上體擁有濃密的淡色班點、眼上明顯的白色眉紋，以及淡黃至橄欖綠色的腳。在渡冬時它們一般結成鬆散的小群，在淺水或泥面探尋昆蟲、甲殼類等小獵物為食，但於合適的生境之下，也會偶然結成數百隻的大群。快來濕地公園，試試你能否在不同種類的鷸中，辨別出林鷸吧！

參考資源：香港濕地公園

The book launch《山野無痕－香港野外活動倫理》 was held successfully at HK Central Library on last Saturday(14/10). Congrats all authors on their book's publication. Thanks our alumnus Dr. Kevin Ho for inviting us again. Hope everyone could learn to love our environment and LEAVE NO TRACE. We are looking forward to more invitations from our alumni to enrich our biological knowledge~

Snake fact #1: Snakes' eyes are lidless
Snake fact #2: The snakes have the wonderful ability to detect scent molecules by flicking their tongues.
Snake fact #3: Snakes are not agressive and only a small portion of them are poisonous

Interested in having close encounters with one of them? Interested in learning how to own one as an alternative pet?

With that said, come to our last activity, the Snake Petting Encounter this Friday lunchtime, 15th May, 2015. We've invited our guest and snake expert, former chairman Gordon Yuen to lead this sharing. Cherish this final opportunity to experience biology!

WYK Biology Club 2014-2015香港觀鳥會塱原生態遊事項

致參與者:
集合時間: 0810開始點名
解散時間: 若1300
集合解散地點: 學校停車場
服飾: 整齊校服+運動鞋 (因當天預測多雨建議穿著防水行山鞋)

請謹記當天參加者是須要上最後三節課。若活動完結後放飯時間不足，學校會讓大家在第七節課堂在校園裡用膳(不得外出)，因此請大家衡量自己的用餐安排。

注意事項:
1. 行程大約2.5小時，整個活動在野外露天進行，活動前請進食豐富早餐，請帶備足夠食水、蚊怕水、防曬用品及雨具(預測當天多雨)。
2. 必須穿著長褲，長襪及運動鞋(行山鞋)，以防紅火蟻咬。
3. 可自備望遠鏡和相機。

請大家準時報到，並在當天遵守本會及導遊的指示。若有同學對該活動有任何查詢或問題，歡迎留言。謝謝!