1、<p><b>　　附 錄</b></p><p><b>　　英文原文及中文翻譯</b></p><p><b>　?。ㄒ唬┯⑽脑?lt;/b></p><p>　　Physics of microwave technology in histochemistry</p>

2、<p>　　L．P．KOK and M．E．BOON.</p><p>　　Institute for Theoretical Physics, University of Groningen, P.O. Box 800, 9700 A V Groningen, The Netherlands Leiden Cytology and Pathology Laboratory, Leiden, The N

3、etherlands</p><p>　　Summary Microwave technology has become important in preparatory techniques for microscopy in many different ways. This paper discusses various aspects of the physics of microwaves, It g

4、ives some theoretical background to understand the practical procedures. Some peculiarities in the optics of microwaves are pointed out, and the practical implications in particular of choosing the size and shape of samp

5、les and containers are discussed. Diffusion rates and chemical-reaction rates increase expone</p><p>　　Introduction</p><p>　　Sample preparation for histochemistry is an art, based on physical a

6、nd chemical processes. Microwaves can influence both processes. In this light, a multidisciplinary team in The Netherlands and some other European countries made an effort to look for benefits of microwave technology in

7、all fields of preparatory techniques. Fruits of this effort are described in detail elsewhere (Boon & Kok, 1988; Kok &Boon, 1990).</p><p>　　Knowledge of both histochemistry and physics is needed to e

8、xploit the potentials of the application of microwave irradiation in histochemistry. Key factors in all preparatory techniques are diffusion (a physical process) and chemical-reaction rates. They are influenced by tempe

9、rature increase, and hence by microwave irradiation. The main effect of microwave irradiation in histochemistry is controllable temperature increase. If microwave irradiation is optimally applied, the resulting microscop

10、i</p><p>　　Some history and the link with optics</p><p>　　About one century ago, in 1888, Hertz discovered that electromagnetic radiation in the microwave and radio regions of the spectrum displ

11、ays the same basic behaviour as visible light. In fact, he showed that 66cm microwaves travel in straight lines, and can be reflected, refracted, and polarized in the same way light waves can. Thus microwaves exhibit dif

12、fraction and interference in the same way as visible light albeit on a different scale of length. The basic unit of length is the wavelength (λ)</p><p>　　of this length scale. Large and small refer to size e

13、xpressed in λ. However, the wavelength of electromagnetic waves depends on the medium in which they propagate. Connected to this is the fact that the velocity of electromagnetic waves within most media is smaller than th

14、e velocity in vacuum or air. A wave has different wavelengths in different media. What remains the same is the frequency of the wave (expressed in Hz, named after Hertz).</p><p>　　The unifying feature of all

15、 electromagnetic waves is that at all frequencies they have the same velocity in vacuum, c. Inside a medium the velocity v air smaller. In air the difference is small: a factor 1.000294. In fact, the factor by which it d

16、iffers depends on the frequency; the quoted figure is for visible light in air. The ratio n = c/v is the refractive index of the medium. For light in water n ≈1.33. Fluid water is a very special substance. At microwave f

17、requencies c/v = 9. This means th</p><p>　　air. For example, for 2.45 GHz microwaves (used in kitchen and laboratory ovens), instead of 12.2cm, λwater is merely 12.2/9 ≈ 1.36 cm. Hence, in microwave applicat

18、ions in an aqueous environment an object is qualified as 'small' when it is smaller than a centimeter. 'Large' means its linear dimension at least exceeds λwater</p><p>　　At low frequencies (

19、e.g., 50Hz mains, or 8MHz personal computer) electromagnetic-radiation aspects of the distribution of electromagnetic energy may be ignored. By contrast, at high frequency (e.g., visible light) these radiation aspects be

20、come dominant. Thinking in terms of lengths: if the characteristic electromagnetic wavelength is much larger than the typical sizes in our system (equipment), we may</p><p>　　ignore radiation aspects. The fu

21、ndamental property of microwave technique is that it considers applications in which the characteristic wavelength is roughly the same size as the system (equipment, circuit . . . . ), or smaller, but yet not so small th

22、at we can merely use optical-ray techniques.</p><p>　　Nevertheless, the lessons from optics can be a useful guide in predicting the behaviour of systems involving media and microwaves. This will be in partic

23、ular the</p><p>　　case when the characteristic wavelength .is smaller than the typical size of the objects involved. The next two sections focus on this optical limit. We shall first discuss the optics of mi

24、crowaves propagating without absorption effects, i.e., we shall first make the simplifying assumption that the penetration depth in media (other than the perfectly reflecting metals) is infinitely large.</p><p

25、>　　Optics of microwaves; reflection and refraction</p><p>　　Perfectly conducting metal surfaces act like perfect mirrors to microwaves. This is the basic principle for the confinement of microwaves inside

26、 the oven chamber of the microwave oven, and for the transport of microwaves inside hollow metal wave guides. At th e interface of two different dielectric media both reflection and refraction take place. Part of the inc

27、ident wave (incident angle i) is reflected with angle of reflection r (with r = i), and another part is transmitted inside the medium. T</p><p>　　the refraction law of Snell: nisin i = nt sin t. Here t is th

28、e angle of refraction, and ni and nt are the refractive indices of the first and the second medium, respectively. In the special case of incidence from vacuum, ni = 1 exactly, and the case of incidence from air, nair≈ 1.

29、 in both cases we effectively have sin i / sin t = n, where n is the relative refractive index, n ≥ 1. There is a fundamental relationship between n and the relative permittivity: n = 時. For water, is anomalously large&

30、lt;/p><p>　　Because there is both reflection and refraction it is of interest to know which fraction Q of a propagating microwave actually enters the object, and which fraction (hence 1-Q) is reflected. The fra

31、ction depends on the polarization of the wave. For waves with the electric-field vector parallel to the interface this fraction is Q1。 In the orthogonal polarization state this fraction is denoted by Q2。 </p><

32、p>　　What does Snell's law teach us in the case of transition from a medium like water to vacuum (or air)? For this transition from medium i (water) to air, one has 9sin iwater = sin t. Unless water is sufficiently

33、 close to zero this equation has no real solution. This means there is no refraction, and thus there is perfect (100%) reflection back into the water. In other words: once the wave is refracted into the convex water mass

34、, there is a great chance it remains caught inside.</p><p>　　Focusing effects and absorption of microwave energy</p><p>　　So far we have discussed the optics of a plane microwave hitting a flat

35、interface between two media. We now turn to curved boundary surfaces. Here again reflection and refraction occur. The curvature of the surface may be used to focus microwaves. For example, a parabolic metallic mirror wil

36、l concentrate microwaves incident parallel to the axis upon reflection in the focal point. Radio telescopes are examples of such mirrors. Similarly, microwave beams refracted at curved surfaces can show a foc</p>

37、<p>　　In Figure 1 we show the results of the ensuing computations for various values of n: n=l, 1.2, 1.4, 4, 9, and∞, respectively. For n=l the material of the sphere is completely microwave transparent. The waves p

38、ass without being deflected. For larger valuesof n the deflection of rays becomes appreciable. For n =1.4 there is 'focusing' on the axis outside the sphere. For n > 2 the focal region has shifted inside the

39、sphere.</p><p>　　With increasing n this effect becomes more pronounced. For n=9 (appropriate for microwaves in fluid water) this focusing effect causes the rays to pass through or very near a point located a

40、t a distance of one ninth of the radius right of the center of the sphere. These plots are universal in the sense that they hold for each size of sphere.</p><p>　　Microwaves, refracted into a medium, in prac

41、tice can be absorbed. To what extent, depends on how large (the imaginary part of the relative permittivity) is. It is a constant of the material and tabulated in the literature. No absorption occurs for = 0: these mate

42、rials are microwave transparent. (Examples are air, Styrofoam, many types of plastic.)</p><p>　　In many practical cases absorption does occur; the waves entering the medium are damped. How much is determined

43、 by the value of , or alternatively by , or the preparation depth d. The wave is damped by the factor exp(-x/d), and hence the intensity as exp(-2x/d), where x is the total distance covered inside the medium. Absorption

44、has, as a direct consequence, the effect of heating up. </p><p>　　Note that the theory that ignores absorption effects gives results completely independent of the actual size of the object, viz. the size of

45、the object in Fig. 1. With</p><p>　　absorption, however, it makes a lot of difference whether d is much larger than the bali radius, or much smaller. In the former case all waves still reach the focal region

46、 with a considerable intensity, and the concentration effect in the central ball region illustrated in the figure is operating very effectively. When d is much smaller than the radius the microwaves will be extinguished

47、completely in the outer region of the ball. Then heating occurs only in the outer shell, before the focusing </p><p>　　Experiments and numerical computations for loads with a high water content have been car

48、ried out by several authors. Kritikos & Schwan (1975) report calculations of diameter and frequency ranges where the maximum heating takes place inside a sphere. At 2.45 GHz a heating concentration in the central reg

49、ion of the ball is obtained for radii between 9mm and 5.5 cm. The focusing effect is a quasi-optical one for radii up to 2 cm, when maximum heating occurs in the centre. For radii over 2cm, the ma</p><p>　　T

50、he distribution of heat generation by microwaves depends on the frequency of the microwaves, and on shape and radius, and dielectric properties of the load. The conditions for occurrence of 'focalized regions', w

51、here maximum heating occurs inside the sphere, are fulfilled for radii and dielectric properties in the range common for kitchen and laboratory items at 2.45 GHz. For large radii within this interval, quasi-optical mecha

52、nisms dominate. For smaller radii, such quasi-optical thinking seem</p><p>　　Figure1 holds for cylinders, too. Here, the focusing effects will be less pronounced than for spherical bodies. (After all, a sphe

53、re has curvature in two directions, a cylinder only in one.) This is confirmed by experiment and computations.</p><p>　　Fig. 1. Plane wave coming from the teft hits bali of dielectficum with a refractive ind

54、ex n = 1, 1.2, 1.4, 4, 9, and ∞. Respectively, individual rays, and the way they are refracted are shown. Not shown are the reflected waves. The value of n is indicated in the figure.</p><p><b>　　（二）中文

55、翻譯</b></p><p>　　組織化學中的物理微波技術</p><p>　　L．P．KOK and M．E．BOON.</p><p>　　理論物理學院，荷蘭格羅寧根大學，Leiden細胞學和病理學實驗室</p><p>　　摘要：微波技術已成為重要的籌備顯微鏡技術在許多不同的方式。本文討論各方面的物理微波，它給出了一些了解實

56、際程序的理論背景。指出了一些特殊的光學微波，而在實際影響，特別討論了選擇樣品和容器的大小和形狀的情況。擴散率和化學反應速率與溫度呈指數增加，因此，在大多數組織化學的程序中，精確的溫度控制是必不可少的。這種由局部加熱的系統(tǒng)，以及溫度傳感器所控制的過程是十分復雜的，但它們可能由于微波輻射的原因而出現(xiàn)。</p><p><b>　　介紹</b></p><p>　　基于物理

57、和化學兩個過程的化學樣品制備是一門藝術。微波能影響這兩個進程。在這種情況下，一個在荷蘭和其他一些歐洲國家多學科小組在各個籌備技術領域做出努力研究，致力于尋找微波技術的益處。這項工作的成果在其他地方做了詳細敘述。</p><p>　　組織化學和物理的知識探索微波輻射在組織化學中的應用潛力。關鍵因素是，所有籌備技術的擴散（物理過程）和化學反應速率。它們是受氣溫升高的影響，因此組織化學中微波輻射的主要任務是控制溫度升高

58、。如果微波輻射得到最佳應用，由于良好的過程控制，產生的顯微圖像也是高清晰的。在本篇文章中做了一些相關物理概念的審定：反射和折射，吸收，駐波效應，熱點，以及微波爐中的溫度控制和溫度測量。</p><p>　　一些光學的歷史與聯(lián)系</p><p>　　大約一個世紀前，也就是1888年，赫茲發(fā)現(xiàn)，電磁輻射中的微波和無線電地區(qū)的頻譜與可見光具有相同的特性。他表明，事實上66cm微波沿直線傳播直線，

59、并且可以被反射，光波可以以同樣的方式折射和偏振。因此微波所顯示的衍射和干涉與可見光的方式是相同的，盡管它們的長度是不同的?；締挝坏拈L度為波長（λ）的輻射，所有物體的微波應用必須衡量這個尺度。大和小是參照λ所表示的大小而定的，然而波長的電磁波取決于他們在介質中的傳播。連接到這是一個事實，即電磁波在大多數媒介的速度小于在真空或空氣中速度。在不同的媒介中波具有不同的波長。仍然保持不變的是波的頻率（用表示赫茲，命名為赫茲）。</p>

60、;<p>　　所有電磁波的統(tǒng)一功能是，在真空中所有頻率具有相同的速度,即光速 C.在介質中速度v較小。它與在空氣中的不同是速度?。阂粋€因素1.000294 。事實上，其中的因素，取決于不同的頻率;引用的數字是對空氣中的可見光。每組的比例的C / V的折射率介質。光與水的介質比例n≈1.33 。流體：水是一個非常特殊的物質。微波頻率的C / ν = 9 。這意味著，折射是異常龐大，而且水中的波長遠小于在空氣中的波長。例如，對

61、于2.45千兆赫的微波（ 廣泛的應用于廚房和實驗室中的微波爐） ，λwater僅僅是12.2/9 ≈ 1.36 cm而不是12.2cm。因此，在水環(huán)境中微波應用的對象是符合‘小'的條件的，它是小于1cm ?！?#39;是指其線性尺寸至少 超過λwater。</p><p>　　在低頻率（例如， 50Hz水管，或8MHz個人電腦）的電磁輻射方面，電磁能量分布可能被忽略。相比之下，在高頻率（例如， 可見光）

62、輻射方面成為主導。按照長度來考慮：如果電磁波波長的特性要遠遠大于在我們的系統(tǒng)（設備）中的一般大小，我們可能會忽略輻射方面。微波技術基本屬性的應用，認為作為一個系統(tǒng)在該特征波長尺寸大致是相同（如設備，電路......） ，或更小，但還沒有如此之小，我們可以僅僅使用光學射線技術。</p><p>　　然而，來自光學的經驗在涉及介質和微波等系統(tǒng)時可以成為指導預測系統(tǒng)一個有用的準則。這是在特征波長小于所涉及的典型物體的大

63、小的情況下的一個特例。在未來兩節(jié)集中討論這一光學限制。我們將首先討論了光學不吸收情況下的微波傳播，即我們應首先做出了簡化假設，即媒介中的穿透深度（完全反射金屬除外）是無窮大。</p><p>　　微波光學：反射和折射</p><p>　　理想導體金屬表面像完美的鏡子，以微波為例。這是禁閉微波烤箱內庭微波爐以及用于運輸微波爐內金屬空心波導的基本原則。在次接口兩種不同介質的媒體都反射和折射進行

64、。部分入射波（入射角i）反射會產生反射波（反射角r=i） ，另一部分是內部的傳播媒介。從而傳播方向一般是改變。衡量反射程度的是斯奈爾定律：nisin i = nt sin t，這里i是入射角，t是折射角，ni和nt分別是第一介質和第二介質的折射率。 在特殊情況下，ni= 1，確切的說來自空氣的介質折射率nair≈ 1 。在這兩種情況下，我們有效地sin i/ sin t = n ，其中 n是相對折射率，n≥ 1 。有一個基本的關系n和相

65、對介電常數：n = 。對水來說水，是異常大的順序號81 ，因此，n ≈ 9 。由于sin i ≤ 1 ，在這種情況下我們會很容易發(fā)現(xiàn)折射角t是永遠不會大于arcsin (1/9) ≈ 。在病理學實驗室其他物質也是常用的，也是相當大，見KOK和BOON的文章（ 1988年） 。因此微波在進入這些材料，將或多或少沿媒介的垂直邊界繼續(xù)傳播。</p><p>　　因為有反射和折射，所以知道Q的哪部分小部分傳播微波實際上進

66、入的對象，哪一部分（因此1 - Q ）是反射是有意思的。這個分數取決于微波的極化特性。對波來說，電場矢量并行接口這部分是Q1，正交偏振態(tài)這一部分指的是Q2。</p><p>　　斯奈爾定律告訴我們，在從像水一樣的介質入射到真空（或空氣）的傳輸情況下。在這種傳輸中，9sin iwater = sin t，除非iwater足夠接近零否則該方程沒有實根。這意味著沒有折射，從而有完善的（ 100 ％ ）反射回水中。換句話

67、說：一旦波折射到凸水中，這是全部陷入其中的一個很好的機會。</p><p><b>　　化學中的微波物理</b></p><p>　　聚焦效應和微波能量吸收</p><p>　　迄今為止，我們討論了光學平面微波觸及兩個平面媒體之間的相互關系。我們現(xiàn)在彎曲邊界表面。在這里反射和折射再次發(fā)生。曲率的表面可以用來聚焦微波。例如，拋金屬反射鏡將集中入射

68、微波沿平行軸應反射在聚焦點。射電望遠鏡也是與之類似的一個例子。同樣，微波光線折射在曲面可以顯示聚焦效應。作為一個范例，讓我們考慮類似于空氣中水的一種球形的介質。這對土豆，番茄，或雞蛋來說是一個極好的模式。同樣，在上一節(jié)中，我們沒有考慮介質內的微波吸收。</p><p>　　圖1中，我們顯示的結果，隨后的計算各種價值觀的n ：n= 1 ,1.2,1.4 ,4.9和∞。n= 1的材料，微波領域是完全透明的，波完全通過

69、沒有偏轉。對于n是一個較大的值時，偏轉射線成為可以觀察到。n = 1.4時焦點位于外表面的軸線商。n=2聯(lián)絡中心區(qū)域轉移到范圍內。隨著n此效應變得更加明顯。對n=9（適合微波在流體水）本集中效應導致射線穿過或非常接近點位于距離九分之一半徑權利的中心領域。從意義上說這些地塊如此的普遍，以至于它們在表面上都占據特定的領域。</p><p>　　折射到介質中的微波，實際上是能夠被吸收的。多大程度上被吸收，取決于虛部的相

70、對介電常數的大小。這是一個恒定的物質，在文獻中有統(tǒng)計。當 = 0沒有吸收發(fā)生，這些是微波透明材料。 （例如，空氣，泡沫塑料，許多類型的塑料。 ）</p><p>　　在許多實際發(fā)生吸收案例,在波進入介質中是會發(fā)生衰減的。衰減的多少是由的值或者是、深度 d決定的。exp(-x/d)決定了波的阻尼衰減，因此，衰減強度就是exp(-2x/d)，其中x表示延伸到介質中的距離。一個直接后果就是吸收導致溫度升高。</p

71、><p>　　需要注意的是忽視吸收的影響的理論使結果完全獨立于物體的實際大小，即圖1所示的物體的大小。然而就吸收而言，它又有大量的差異，是否深度d是遠遠大于巴厘半徑，還是更小。在前一種情況下，所有波傳播到中心區(qū)域仍然具有相當的強度，圖像中在球中心地區(qū)聚焦作用說明這是非常有效。當d遠小于半徑時，微波在球的外部區(qū)域將完全消失。在聚焦點可能產生任何重大影響之前，加熱只發(fā)生在外殼。</p><p>　

72、　一些作者進行了高水分含量負載的實驗和數值計算。Kritikos & Schwan（ 1975年）的報告計算的直徑和頻率范圍的最高暖氣發(fā)生在一個領域。在2.45 GHz的供暖系統(tǒng)中集中在中部地區(qū)的球獲得9mm到5cm之間的半徑。聚焦效應是一個半徑高達2厘米準光，最大加熱發(fā)生在該中心。當半徑超過2厘米時，最大供熱區(qū)域從中心向表面緩慢運行。Ohlsson and Risman（ 1978 ）利用紅外熱像照射伴隨有國內微波爐所使用的2

73、.45 GHz的微波產生。對于幻象的食物，肉和馬鈴薯等，他們分別使用，36-i，16，60 –i20，他們觀察實驗得到核心半徑在1～1.8cm之間時熱效應最為顯著。對于半徑2.5cm仍然有一個明顯的聚焦效應。對于一個半徑近4cm，表面加熱更加明顯高于核心暖氣，這與普通滲透深入的概念是相統(tǒng)一的。</p><p>　　分配所產生的熱量取決于微波頻率的微波，以及形狀和半徑，和介電性能的負載。發(fā)生聚焦地區(qū)即發(fā)生最大暖氣的

74、領域條件是應用于廚房和實驗室項目的2.45GHz微波的各種常見半徑和介電常數來實現(xiàn)的。對于在此區(qū)間的大型半徑，準光學機制占主導地位。對于較小的半徑，例如準光學思想似乎已經沒有什么意義。然而，由于內部共振，在這種情況下核心暖氣就可能發(fā)生，駐波效應是入射波和反射波之間的干擾所造成的現(xiàn)象。</p><p>　　圖1 若表示圓柱面，在這里，聚焦效應不如球面結構明顯。（畢竟一個球體已在兩個方向彎曲，而圓柱面只有一個。）這一