Forward:不一樣的語錄

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Molecular biology and basic techniques

Introduction
one of the key marcomoecular elements essential for the maintenance, integrity and functioning of all cells is proteins. Proteins are an essential yet diverse group of biomolecules encompassing enzymes, antibodies, transport and structural proteins, to name but a few. The synthesis of proteins is itself catalysed by enzymes and proteins; however, this process is ultimately directed by genetic material deoxyribonucleic acid or DNA. DNA encodes all the information needed to specify the structure of every protein the cell can produce. The realisation that DNA lies behind all the cell's activities led to the development of molecular biology. Rather than a discrete area of biosciences, molecular biology is now accepted as a very important means of understanding and describing complex biological processes. The development of the methods and techniques to study processes at the molecular level has led to new and powerful ways of isolating, analyzing, manipulating and exploiting nucleic acids. It has also given rise to the development of new and exciting areas of the biological sciences such as biotechnology, genome mapping, molecular medicine and gene therapy.
In considering the potential utility of molecular biological techniques it is important to understand some of the fundamental attributes of the structures of nucleic acids and gain an appreciation of the how this dictates the function in vivo and in vitro. Indeed many techniques used in molecular biology mimic in some way the natural functions of nucleic acids, such as replication and transcription. This chapter is therefore intended to provide an overview of the general features of nucleic acid structure and function and describe some of the basic methods used in its isolation and analysis.

狼來了的結果

他與她在大草原遇見。
他是一位牧羊人，尋找一隻命中註定要看顧的綿羊；
她是一隻綿羊，尋找一位可以照顧她的人。
因為牧羊人與羊一起生活。

但是現實大草原上有一隻大灰狼，它終有一天會來找他們。
那時候牧羊人與羊要接受考驗，
看看他們是否真正需於對方。
成功戰勝了大灰狼，他們便能永遠一齊在大草原生活；
失敗了，各自都會受傷，他們會分離。

羊十分害怕這一天的來臨，她占卜，她幻想，她對自己對牧羊人沒有信心。
因為她是綿羊，雪白的羊毛下的皮肉脆弱細薄，只要受狼一爪，肉破血流後便會死去。

牧羊人也擔心狼的來臨，但是他樂觀地相信這一天最少二三年才來臨。
這兩年他要與羊開心地過，他要以對羊的細心照顧，令羊對他有十足的信心。

牧羊人不時嚇羊，想知道羊有沒有增加對其的信心。
他呼：「狼來了！」
而且呼了兩次。
羊受驚，生氣了。

她想報復，也呼起--狼來了。

然而這一次，狼真的來了。
牧羊人吃了一驚，魂魄未定。
萬萬都沒有想到狼會來得這麼快，才三個月的光陰。
是初次看見到狼? 是擔心羊受了傷害？是對突如其來的衝擊而不敢相信?
牧羊人失去了冷靜的心，不斷掙扎，不斷揮動手中的小刀，希望能趕走狼，
他希望通過這次考驗，
他太愛羊了，不想失去她！

...羊受傷了，而且是被小刀所傷。羊傷得很重，血和淚沒有停止流過，
牧羊人失敗了，完全地。

羊受傷後，離開了牧羊人，永遠離開這個傷心之地。
牧羊人曾努力挽留羊，但羊回應說：「你有能力照顧我嗎？」
就是這一句，牧羊人呆下了。.......... 　

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Production of Bacitracin (a polypeptide antibiotic)

Units for medium preparation
1. Seed cooker and 2. Fermentor:
    Cook and sterilize medium for the seed/production fermentors. The name "cooker" implies "cook meals" for the organisms, which breaks down large molecules such as starch and proteins into small ones suitable for fermentation by heating and alkaline hydrolysis.
3. Hot water tank
  Containing the hot water to be used for the cooker

 Inoculum preparation: by seed tank or intermediate seed tank (to grow the organisms in a smaller culture vessel to be used a seed for a larger vessel)
4. Mash cooler: To cool down the mash from cooker and utilize the heat to heat up water.

Units for inoculum preparation:
5. Intermediate culture tank
     to prepare inoculum for seed tank,
6. seed tank
     for the large fermentor. (The intermediate tank is seeded with flask culture.)

Downstream processing units-- Isolation of the products: by the centrifugal extractor.

7. Filter press: to remove cell debris by filtration. Removal of insoluble components.
8. Char adsorption:  removal of impurities from the product solution. Purification product

Microscopy -- Introduction

Biochemical analysis is frequently accompanied by microscopic examination of tisse , cell or organelle preparations. Such examinations are used in many different applications; for example, to evaluate the integrity of samples during an experiment, to map the fine details of the spatial distribution of macromolecules within cells, or to directly measure biochemical events within living tissues.

There are two fundamentally different types of microscope; the light microscope and the electron microscope.Light microscopes use a series of glass lenses to focus light in order to form an image whereas electron microscopes are electromagnetic lenses to focus a beam of electrons. Light microscopes are able to magnify to a maximum of approximately 1500 times whereas electron microscopes are capable of magnifying a maximum of approximately 200000times.

Magnification is not, however, the best measure of a microscope. Rather resolution, the ability to distinguish between two closely spaced points in a specimen, is much more reliable estimate of a microscope’s utility. Light microscopes have a resolution limit of about 0.5 micrometres (um) for routine analysis. In contrast, electron microscopes have a resolutions of up to 1 nanometre (nm). Both living and dead specimens are viewed with an electron microscope, and often in real color, whereas only dead ones are viewed with an electron microscope, and never in real color. Recent advancements have improved upon the 0.2um resolution limit of the lgith microscope for some special applications.

Applications of the microscope in biochemtry may be relatively simple and routine; for example, a quick check of the status of a cell preparation or of cells growing in tissue culture. Here, a simple bench-top

盲目投資 抗通脹不成反蝕錢

理財多面睇　李兆波 4月 21日 星期四

近期市民關注的焦點是通脹升溫，與普羅大眾息息相關的衣食住行樣樣加，但偏偏人工加幅追不上通脹。通脹的厲害之處是在不知不覺間降低市民購買力及生活質素。

筆者記得二十多年前，一碗淨河粉賣一點5元，現在平均最少12元，可見物價飛升。


朋友A的父親在六十年代月入300元，相較當年其他人平均月薪百多元，朋友A的父親是非常富有。朋友A說當年新蒲崗的單位不超過一萬元，無論是首期或是日後的按揭供款，他的父親都能從容應付。可是朋友A的父親覺得「拿著現金」更為實在，加上對通脹及貶值等知識缺乏認知，

所以朋友A的父親沒有買樓。40多年後，結果大家都可猜想得到，朋友A的父親退休後，僅靠當時很龐大、但現已貶值的積蓄，過著省吃儉用的生活，更不用說新蒲崗部分新落成的單位呎價已超過1萬元（當然房屋質素、面積及景觀不能直接比較）。

通脹加劇，現金不斷貶值，購買力下降。因此，不少人會把資金投入資產市場，對抗通脹，連平時不作投資的人，也會在身邊其他人的耳濡目染下，膽粗粗地投資起來。可是，不作分析、只是人云亦云地盲目投資，不單未能對抗通脹，更可能將辛苦累積的金錢白白損失，把錢掉進咸水海。
筆者身邊一些年輕、投資經驗淺的朋友，特別喜歡投資三、四線或創業板的股票。筆者不是說這些股票不好，而是投資這些股票需要更深入的分析，以判斷哪些是有潛力的優質股，哪些是避之則吉的股票。

朋友B早前購買一隻有本地零售業務的股票，但他並沒有分析便高位入貨，結果股價不斷下跌，更甚是股票十合一後，股價續跌，令他損失慘重。但他沒有反省，轉過頭重蹈覆轍。他聽到其他朋友的「消息」，便購買某隻創業板股票，起初他真的賺錢（不過數百元），所以他投入更多金錢在那隻「消息股」，結果股價下挫，金錢化為烏有。
相對購買消費品，你都會貨比三家，又會在同類貨品挑選，把最美、最優質的貨品買回家。何況你現在用的是你辛勤工作得來的金錢，用來投資就應該更加謹慎。投資不是購入「金額細、看上去便宜」的股票，而是買一些有投資價值的股票。如果朋友B將儲蓄購買藍籌股如內銀股，連股息及股價升幅，在過去一年要爭取25%回報不難，這總比將儲蓄分作多份，然後買些「注碼細」但近乎賭博的股票更佳。
李兆波
中大酒店及旅遊管理學院會計及財務高級導師

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筆者論點都正確, 但以二十多年前，一碗淨河粉賣一點5元，現在平均最少12元，來得出物價飛升, 我覺得有些不切合。五年內的物價比較已經好明顯，用到二十年前，比我感覺如果今天與遠古比。
人工不加是事實，特別是對於長工來說。長工五年都沒有加人工，相反，一些實力派在不斷跳槽下，人工暴升。在些不是叫人跳槽，不過大多數老闆都不會主動加價，因為通漲都令成本增加!
唉打工仔同老闆都成為通漲的受害者。但是有人受害者必有人受益，誰是通漲的受益者?下回分解。
完

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Applications of Ultrafiltration

Although dialysis is still used occasionally as a purification tool, it has been largely replaced by gel filtration adn ultrafiltration techniques. The major disadvantage of dialysis that is overcome by the newer method is that it may take several days of dialysis to attain a suitable separation. The other methods require 1-2 hours or less.
Ultrafiltration involves the separation of molecular species on the basis of size, shape, and/or charge. The solution to be separated is forced through a membrane under teh influence of high pressure or centrifual force. Membranes may be chosen for optimum flow rate, molecular specificity, and molecular weight coutoff. Two applications of membrane filtration are obvious:
1) desalting buffers or other solutions and
2) clarification of turbid solutions by removal of micron- or submicron- sized particles. Other applications are discussed below.
Membrane filters are divided into two major classes, depth and screen. Depth filters, which may be composed of paper, cotton, or fiberglass, function by trapping particles primarily within the "depths" of the filter matrix. The interior of these filters is a random arrangement of fiber material forming tiny channels. Particles that are larger than the passages are retained in the filter by entrapment in the matrix. Since they are thick, depth filters have a high load capacity, retaining particles both on the surface and within teh matrix. In adddition, they have relatively high flow rates, are inert to most solvents, and are inexpensive. Howeverm they have several disadvantages, including
1) ill-defined and variable pore sizes due to a random matrix,
2) exxtensive absorption and loss of liquid filtrate, and
3) loss of filter fragments that contaminate the filtrate.

Many of these disadvantages are overcome by screen filters, which have uniform pore size. The screen filters function by retaining particles on their surfaces rather than within the matrix. The most widely used screen-type filters are composed of polycarbonate and cellulose esters (cellulose nitrate adn acetate). Membrane filters of these materials can be manufactured with a predetermined and accurately controlled pore size. Filters are available with a mean pore size ranging from 0.025 to 15 um. These filters clog more readily than do depth filters and require suction, pressure, or centrifugal force for liquid flow. A typical flow rate for the commonly used 0.45 -um membrane is 57 mL min-1 cm-2 at 10 psi. Clogging can be reduced by combining depth and screen filters. The depth filter serves as a "prefilter" to remove particles that would rapidly clog the screen filter.

Ultrafiltration devices are available for macroseparations (up to 50 L) or for microseparations (milli- to microliters). For solutions larger than a few milliliters, gas-pressurized cells or suction-filter devices are used. For concentration and purification of samples in the milli- to microliter range, disposable filters are available. These devices, often called microconcentrators, offer the user simplicity, time saving, and high recovery. The sample is placed in a reservoir above the membrane and centrifuged in a fixed-angle rotator. The time and centrifugal force required depend on the membrane, with spin times varying from 30 minutes to 2 hours and forces from 1000 x g to 7500 x g. These are available from a variety of sources, including Schleicher and Schuell, Bio-Rad, Pierce, Amicon, and Millipore.
The principles behind ultrafiltration are sometimes misunderstood. The nomenclature implies that separation are the result of physical trapping of the particles and molecules by teh filter. With polycarbonate and fiberglass filters, separations are made primarily on teh basis of physical size. Other filters (cellulose nitrate, polyvinylidene fluoride, and to a lesser extent cellulose acetate) trap particles that cannot pass through the pores, but also retain macromolecules by adsorption. In particular, these materials have protein and nucleic acid bingin properties. Each type of membrance displays a different affinity for various molecules. For protein, the relative binding affinity is polyvinylidene fluoride > cellulose  nitrate > cellulose acetate. We can expect to see many applications of the "affinity membranes" in the future as the various membrane surface chemistries of macromolecules and quantitative binding assays.