Shadowing Practice: 2 The Principle of the Electron Microscope - Learn English Speaking with Video
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105 cümleler
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1
How does such a microscope work?
Bu tür bir mikroskop nasıl çalışır?
2
The optical microscope has been known since the 17th century.
3
The modern optical microscope has magnification of about 10,000 times and makes it possible for the human eye to distinguish objects that are two ten-thousandths of a millimeter away from each other.
4
It is this resolving power of the microscope, i.e.
Mikroskobun çözünürlük gücü işte budur, yani;
5
the ability to distinguish two very close objects in an image, which is one of the most important parameters.
Görüntüdeki birbirine çok yakın iki nesneyi ayırt edebilme yeteneği, en önemli parametrelerden biridir.
6
The level of magnification just makes it possible to picture how the image was enlarged.
Büyütme düzeyi, görüntünün nasıl büyütüldüğünü hayal etmeyi mümkün kılıyor.
7
However, it does not say whether we can see anything in the picture.
Ancak resimde bir şey görüp göremeyeceğimiz belirtilmiyor.
8
A human eye, at its best, has only a resolution of 0.2 millimeters, while the optical microscope has two ten-thousandths of a millimeter, and the electron microscope has up to 50 picometers.
İnsan gözünün en iyi çözünürlüğü yalnızca 0,2 milimetre iken, optik mikroskobun çözünürlüğü milimetrenin on binde ikisi, elektron mikroskobunun ise 50 pikometreye kadar çıkmaktadır.
9
Wait a minute.
Bir dakika bekle.
10
That's too many numbers.
Bu çok fazla sayı.
11
Well, it's as if you were watching a tennis match from the moon and were still able to follow the small tennis ball.
Şöyle düşünün, sanki ayda bir tenis maçını izliyorsunuz ve yine de küçük tenis topunu takip edebiliyorsunuz.
12
Mmm, interesting.
Hmm, ilginç.
13
Let's go back to the optical microscope.
Optik mikroskoba geri dönelim.
14
When attempting to reach a better resolution, scientists encountered the limit of the wavelength of the light used for the illumination of the sample.
15
It was not possible to distinguish points closer than several hundreds of nanometers.
16
In 1920, it was discovered that accelerated electrons in a vacuum can act as light, while the wavelength of these electrons is about 100,000 times smaller than light.
17
It was also discovered that electric and magnetic fields influence electrons similarly to how lenses and mirrors influence the light.
18
Hey, who is this handsome fellow?
19
That's Dr.
20
Ernst Ruska, who assembled the first electron microscope in 1931, and after more than 50 years, he was awarded the Nobel Prize for Physics for his invention.
21
Well, the main thing is that he lived to receive it.
22
I am still waiting.
23
I would still like to know what an electron actually is.
24
An electron is the negatively charged particle of an atom orbiting around the nucleus.
25
It can be released by heat or an electric field.
26
Electrons are 2,000 times lighter than the smallest atom.
27
Thus, they can easily be stopped or diverted when hitting materials.
28
Now I see.
29
That's why there must be a vacuum in the microscope.
30
Great!
31
The column of the electron microscope consists of basically the same parts as the optical one.
32
However, the source of light is replaced by the so-called electron guns and the glass lenses by electromagnetic ones.
33
The electron beam is produced by an electron gun, in which, for example, a tungsten filament can be placed as the electron source.
34
The beam is produced by heaving the filament up to 2700 degrees Celsius and connecting it to high voltage.
35
The higher the voltage, the higher the energy of the electrons.
36
The electrons accelerated by 300 kilovolts almost reach the speed of light.
37
However, to reach a high resolution, the accelerating voltage and series of lenses must be immensely stable.
38
stable.
39
The power cabinet contains a number of sources whose output voltage or current fluctuate not more than one millionth of the output value.
40
I probably understand, but don't you have another example?
41
The one with Tinnis was excellent.
42
I do.
43
Try to imagine that the allowed voltage fluctuation in a common socket has the height of Mount Everest.
44
Then, the allowed voltage fluctuation of a 200 kilovolt high voltage source has the height of only 7 centimeters.
45
Such stability needs very efficient and sophisticated electronic circuits.
46
You see how good you are with examples?
47
Let's go on.
48
Since electrons move freely only in a vacuum, there must be a vacuum in the entire column.
49
To achieve this, vacuum pumps are used.
50
Various levels of vacuum are needed.
51
The highest is around the electron gun.
52
The difference between common air pressure and residual pressure in the microscope is about 10 orders of magnitude.
53
So it means that the probability that an electron will hit an air molecule under this pressure when passing through the column is zero?
54
Yes, almost zero.
55
However, dozens of millions to billions of electrons hit the samples per second.
56
Poor lizard.
57
Electromagnetic lenses focus the electron beam on the examined sample in an optimal way.
58
During its entire journey, the electron beam goes through a number of apertures with various diameters.
59
The smallest ones can be just a few thousandths of a millimeter.
60
These apertures stop electrons undesirable for creating the image.
61
The electron beam hits the observed object and it either scans its surface step by step as if it were reading an inscription on the wall with a torch at night or it goes through the sample and shows its inner structure.
62
I see and according to the way the electron beam hits the sample we distinguish two basic types of electron microscopes scanning and and transmission.
63
Exactly.
64
The sample for the transmission electron microscope is very thin, several hundred nanometers, and it is placed on a grid.
65
If it wasn't thin, electrons would be stopped and no image would be created in the transmission microscope.
66
There are various holders available for the examination of samples in the transmission microscope.
67
depending on the application a customer would like to use.
68
Here we can see a holder where more samples can be placed at the same time.
69
On the other hand, the sample examined in the scanning microscope can be bigger, even dozens of centimeters.
70
Therefore, the scanning microscope is always used where information about the surface of the sample is required.
71
Yes, the only requirement is that the sample must withstand a vacuum and the irradiation with electrons.
72
A holder is not necessary.
73
Samples are placed in a small table which is placed under the electron column.
74
As soon as the electron beam hits the sample or scans through it, various detectors placed in the microscope create the final image.
75
And can I manipulate the sample placed this way in the microscope?
76
You are right that it is not enough to move most of the examined objects along a horizontal axis.
77
Information can be gained from various depths of the sample and we can observe them if we slightly turn the sample.
78
The sample holder in the transmission microscope is inserted through a vacuum interlock in the goniometer.
79
This enables not only movement along the X and Y axes, but also its inclination around one or both axes.
80
Also, the rotation or movement along the z-axis in parallel to the electron beam.
81
Phew!
82
That sentence is a little complicated.
83
It would be enough to say, yes, it's possible.
84
We'd better move on.
85
What influences the quality of the picture?
86
The image quality in the scanning microscope depends on the orientation and distance of the sample from detectors and the final lens.
87
The stage on which the sample is placed makes it possible to move it vertically along the x and y axes, up and down in the direction of the z-axis, and with a possible inclination and rotation.
88
These movements are performed with step motors and are controlled by the computer.
89
Great, but show me some pictures already.
90
Biologists use electron microscopes to examine the structure of cells, bacteria, viruses, and colloidal particles.
91
Scientists who are concerned with material characteristics want to observe inhomogenities and faults in metals, crystals, and ceramic materials.
92
In geological fields, the electron microscope allowed the detailed studies of rocks, minerals, and fossils, and to understand the origin of our planet and its valuable mineral resources.
93
electron microscopes not only display, but also analyze, measure, and modify in 2D, 3D, and even 4D.
94
Wait, I know it here.
95
This is Satek in Brno, Central European Institute of Technology.
96
Yes, there is a Kryos electron microscope here with a special function.
97
It can work with biological samples.
98
They would soon be dehydrated by the vacuum in the common electron microscope and thus would be destroyed for the research.
99
However, FEI has developed a system where each sample is permanently frozen to at least the temperature of liquid nitrogen, from its production to its examination in the Kryos microscope.
100
I understand.
101
Thus, the damage is prevented.
102
Thanks to the transmission electron microscope Titan Kryos, created by the direct electron electron detector Falcon 2, we can determine the structures of virus, or protein complexes, with very high resolution.
103
The structure with very high relationship is very important to our work, because it can be explained to us, for example, the mechanism of infection, in case of virus, or the mechanism of action of protein complexes that are involved in the important biological behavior of the unit.
104
The risk of the microscope Kryos is its external stability, which can be done a long-term measurement, the capabilities of cannot-optctic mode, without any protection of ve Pla Premium service of случае.
105
Therefore we can discuss more qualityberson more information in the meantime of the battery to perform contract and effectively use sound performance in the video는 which increases our LingQ Gold strive by gig security.
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Bu dersin kelimeleri ve konuşma notları
Bu C2 seviyesindeki konuşma dersi “2 The Principle of the Electron Microscope” videosuna dayanıyor. En çok tekrarlanan kelimeler: electron, microscope, sample, vacuum, beam. Bu videoda gölgeleme çalışması için 105 cümle ve 1498 kelime var. Konuşma bölümü 10:07 sürüyor. Konuşmacı dakikada yaklaşık 148 kelimelik dengeli bir hızla konuşuyor; gölgeleme için rahat bir tempo. Kelimelerin yalnızca %75’i İngilizcede en sık kullanılan 3.000 kelime arasında, bu yüzden kelime dağarcığı zorlayıcı.
Bu videodaki önemli kelimeler
Videodaki en ileri düzey 15 kelime, telaffuzu ve anlamıyla:
| Kelime | Telaffuz | Anlam |
|---|---|---|
| microscope isim | /ˈmaɪ.kɹəˌskoʊp/ | mikroskop |
| electron isim | /ɪˈlɛk.tɹɑn/ | elektron |
| vacuum isim | /ˈvæ.kjuːm/ | vakum |
| voltage isim | /ˈvəʊltɪd͡ʒ/ | gerilim |
| distinguish fiil | /dɪˈstɪŋ.ɡwɪʃ/ | ayırt etmek, ayırmak |
| millimetre isim | milimetre | |
| thousandth sıfat | /ˈθaʊzən(d)θ/ | bininci |
| accelerate fiil | /ɪkˈsɛl.əˌɹeɪt/ | hızlandırmak |
| axe isim | /æks/ | balta |
| axis isim | /ˈæksɪs/ | eksen |
| fluctuation isim | /flʌkt͡ʃuːˈeɪʃən/ | dalgalanma |
| wavelength isim | /ˈweɪvˌlɛŋ(k)θ/ | dalga boyu |
| electromagnetic sıfat | /ɪˌlɛk.tɹoʊ.mæɡˈnɛ.tɪk/ | elektromanyetik |
| atom isim | /ˈætəm/ | atom |
| particle isim | /ˈpɑɹtək(ə)l/ | parçacık |
Tekrar etmeye değer cümleler
Videodan, günlük konuşmada yeniden kullanabileceğiniz kısa ve tam cümleler:
- Let's go back to the optical microscope.
- I probably understand, but don't you have another example?
- You see how good you are with examples?
Bu videodaki dil bilgisi
Konuşmacının en çok kullandığı yapılar, videodaki sözcüklerin aynısıyla:
| Yapı | Videoda |
|---|---|
| Edilgen yapı be + fiilin üçüncü hâli — kimin yaptığı değil, ne olduğu önemli | has been known · was enlarged · was discovered |
| İlgi cümlecikleri who / which + cümle — bir kişi ya da şey hakkında ek bilgi | image, which is · table which is · stability, which can |
| Present perfect have/has + fiilin üçüncü hâli — geçmişte olan ama şimdi de önemli olan bir eylem | has been known · has developed |
Dikkat edilecek telaffuzlar
Konuşmacı don't, wasn't, we'd gibi kısaltılmış biçimleri 3 kez kullanıyor. Bunları duyduğunuz gibi kısa söyleyin.
- “th” sesleri: thousandth /ˈθaʊzən(d)θ/, wavelength /ˈweɪvˌlɛŋ(k)θ/, millionth /ˈmɪljənθ/, withstand /wɪðˈstænd/
- “sh” ve “zh” sesleri: distinguish /dɪˈstɪŋ.ɡwɪʃ/, fluctuation /flʌkt͡ʃuːˈeɪʃən/, inclination /ˌɪn.klɪˈneɪ.ʃən/, magnification /ˌmæɡnɪfɪˈkeɪʃən/, rotation /ɹoʊˈteɪʃən/
- Uzun kelimeler — vurguyu doğru yere koyun: accelerate /ɪkˈsɛl.əˌɹeɪt/, fluctuation /flʌkt͡ʃuːˈeɪʃən/, inclination /ˌɪn.klɪˈneɪ.ʃən/, magnification /ˌmæɡnɪfɪˈkeɪʃən/, electromagnetic /ɪˌlɛk.tɹoʊ.mæɡˈnɛ.tɪk/
Türkçe konuşanların zorlandığı sesler:
- /w/ — dudaklar yuvarlak, /v/ değil: distinguish /dɪˈstɪŋ.ɡwɪʃ/, wavelength /ˈweɪvˌlɛŋ(k)θ/, withstand /wɪðˈstænd/
- Kelime başındaki ünsüz kümesi — araya ünlü eklemeyin: scan /skæn/, fluctuation /flʌkt͡ʃuːˈeɪʃən/, fluctuate /ˈflʌkt͡ʃu.eɪt/, strive /ˈstɹaɪv/, probability /ˌpɹɑ.bəˈbɪl.ə.ti/
- /æ/ — “e”den daha açık: vacuum /ˈvæ.kjuːm/, scan /skæn/, axe /æks/, axis /ˈæksɪs/, aperture /ˈæp.ɚˌt͡ʃʊɹ/
Bu videoyla nasıl çalışılır
- Videonun tamamını konuşmadan bir kez dinleyin ve bilmediğiniz kelimeleri not edin.
- Normal hızda cümle cümle tekrar edin; ritminiz konuşmacıyla aynı olana kadar her cümleyi yineleyin.
- Kendinizi kaydedin ve orijinaliyle karşılaştırın; microscope, electron, vacuum gibi kelimelere özellikle dikkat edin.
Gölgeleme Tekniği Nedir?
Gölgeleme, başlangıçta profesyonel tercüman eğitimi için geliştirilen ve çok dilli Dr. Alexander Arguelles tarafından popüler hale getirilen, bilim destekli bir dil öğrenme tekniğidir. Yöntem basit ama güçlüdür: ana dili İngilizce olan bir sesi dinler ve hemen yüksek sesle tekrar edersiniz — konuşmacıyı 1-2 saniye gecikmeyle takip eden bir gölge gibi. Pasif dinleme veya dilbilgisi alıştırmalarının aksine, gölgeleme beyninizi ve ağız kaslarınızı gerçek konuşma kalıplarını eşzamanlı olarak işlemeye ve yeniden üretmeye zorlar. Araştırmalar, telaffuz doğruluğu, tonlama, ritim, bağlı konuşma, dinleme anlama ve konuşma akıcılığını önemli ölçüde geliştirdiğini göstermektedir — bu da onu IELTS Konuşma hazırlığı ve gerçek dünya İngilizce iletişimi için en etkili yöntemlerden biri yapar.