In nuclear physics and nuclear chemistry, a nuclear reaction is a process in which two nuclei, or a nucleus and an external subatomic particle, collide to produce one or more new nuclides. Thus, a nuclear reaction must cause a transformation of at least one nuclide to another. If a nucleus interacts with another nucleus or particle and they then separate without changing the nature of any nuclide, the process is simply referred to as a type of nuclear scattering, rather than a nuclear reaction.

In principle, a reaction can involve more than two particles colliding, but because the probability of three or more nuclei to meet at the same time at the same place is much less than for two nuclei, such an event is exceptionally rare (see triple alpha process for an example very close to a three-body nuclear reaction). The term "nuclear reaction" may refer either to a change in a nuclide induced by collision with another particle or to a spontaneous change of a nuclide without collision.

Natural nuclear reactions occur in the interaction between cosmic rays and matter, and nuclear reactions can be employed artificially to obtain nuclear energy, at an adjustable rate, on-demand. Nuclear chain reactions in fissionable materials produce induced nuclear fission. Various nuclear fusion reactions of light elements power the energy production of the Sun and stars.

History
In 1919, Ernest Rutherford was able to accomplish transmutation of nitrogen into oxygen at the University of Manchester, using alpha particles directed at nitrogen 14N + α → 17O + p.  This was the first observation of an induced nuclear reaction, that is, a reaction in which particles from one decay are used to transform another atomic nucleus. Eventually, in 1932 at Cambridge University, a fully artificial nuclear reaction and nuclear transmutation was achieved by Rutherford's colleagues John Cockcroft and Ernest Walton, who used artificially accelerated protons against lithium-7, to split the nucleus into two alpha particles. The feat was popularly known as "splitting the atom", although it was not the modern nuclear fission reaction later (in 1938) discovered in heavy elements by the German scientists Otto Hahn, Lise Meitner, and Fritz Strassmann.

Nuclear reaction equations

Nuclear reactions may be shown in a form similar to chemical equations, for which invariant mass must balance for each side of the equation, and in which transformations of particles must follow certain conservation laws, such as conservation of charge and baryon number (total atomic mass number). An example of this notation follows:

:{| border="0"
|- style="height:2em;"
| ||+ || ||→ || ||+ ||?.
|}
To balance the equation above for mass, charge and mass number, the second nucleus to the right must have atomic number 2 and mass number 4; it is therefore also helium-4. The complete equation therefore reads:
:{| border="0"
|- style="height:2em;"
| ||+ || ||→ || ||+ ||.
|}
or more simply:
:{| border="0"
|- style="height:2em;"
| ||+ || ||→ ||2 .
|}

Instead of using the full equations in the style above, in many situations a compact notation is used to describe nuclear reactions. This style of the form A(b,c)D is equivalent to A + b producing c + D. Common light particles are often abbreviated in this shorthand, typically p for proton, n for neutron, d for deuteron, α representing an alpha particle or helium-4, β for beta particle or electron, γ for gamma photon, etc. The reaction above would be written as 6Li(d,α)α.

Energy conservation
Kinetic energy may be released during the course of a reaction (exothermic reaction) or kinetic energy may have to be supplied for the reaction to take place (endothermic reaction). This can be calculated by reference to a table of very accurate particle rest masses, as follows: according to the reference tables, the  nucleus has a standard atomic weight of 6.015 atomic mass units (abbreviated u), the deuterium has 2.014 u, and the helium-4 nucleus has 4.0026 u. Thus:
 the sum of the rest mass of the individual nuclei = 6.015 + 2.014 = 8.029 u;
 the total rest mass on the two helium-nuclei = 2 × 4.0026 = 8.0052 u;
 missing rest mass = 8.029 – 8.0052 = 0.0238 atomic mass units.

In a nuclear reaction, the total (relativistic) energy is conserved. The "missing" rest mass must therefore reappear as kinetic energy released in the reaction; its source is the nuclear binding energy. Using Einstein's mass-energy equivalence formula E = mc2, the amount of energy released can be determined. We first need the energy equivalent of one atomic mass unit:
 1 u c2 = (1.66054 × 10−27 kg) × (2.99792 × 108 m/s)2
 = 1.49242 × 10−10 kg (m/s)2 = 1.49242 × 10−10 J (joule) × (1 MeV / 1.60218 × 10−13 J)
 = 931.49 MeV,
 so 1 u c2 = 931.49 MeV.

Hence, the energy released is 0.0238 × 931 MeV = 22.2 MeV.

Expressed differently: the mass is reduced by 0.3%, corresponding to 0.3% of 90 PJ/kg is 270 TJ/kg.

This is a large amount of energy for a nuclear reaction; the amount is so high because the binding energy per nucleon of the helium-4 nucleus is unusually high because the He-4 nucleus is "doubly magic". (The He-4 nucleus is unusually stable and tightly bound for the same reason that the helium atom is inert: each pair of protons and neutrons in He-4 occupies a filled 1s nuclear orbital in the same way that the pair of electrons in the helium atom occupy a filled 1s electron orbital). Consequently, alpha particles appear frequently on the right-hand side of nuclear reactions.

The energy released in a nuclear reaction can appear mainly in one of three ways:
kinetic energy of the product particles (fraction of the kinetic energy of the charged nuclear reaction products can be directly converted into electrostatic energy);
emission of very high energy photons, called gamma rays;
some energy may remain in the nucleus, as a metastable energy level.

When the product nucleus is metastable, this is indicated by placing an asterisk ("*") next to its atomic number. This energy is eventually released through nuclear decay.

A small amount of energy may also emerge in the form of X-rays. Generally, the product nucleus has a different atomic number, and thus the configuration of its electron shells is wrong. As the electrons rearrange themselves and drop to lower energy levels, internal transition X-rays (X-rays with precisely defined emission lines) may be emitted.

Q-value and energy balance
In writing down the reaction equation, in a way analogous to a chemical equation, one may, in addition, give the reaction energy on the right side:
Target nucleus + projectile → Final nucleus + ejectile + Q.

For the particular case discussed above, the reaction energy has already been calculated as Q = 22.2 MeV. Hence:

 {| border="0"
|- style="height:2em;"
| ||+ || ||→ ||2  ||+ ||22.2 MeV.
|}

The reaction energy (the "Q-value") is positive for exothermal reactions and negative for endothermal reactions, opposite to the similar expression in chemistry. On the one hand, it is the difference between the sums of kinetic energies on the final side and on the initial side. But on the other hand, it is also the difference between the nuclear rest masses on the initial side and on the final side (in this way, we have calculated the Q-value above).

Reaction rates
If the reaction equation is balanced, that does not mean that the reaction really occurs. The rate at which reactions occur depends on the energy and the flux of the incident particles, and the reaction cross section. An example of a large repository of reaction rates is the REACLIB database, as maintained by the Joint Institute for Nuclear Astrophysics.

Charged vs. uncharged particles
In the initial collision which begins the reaction, the particles must approach closely enough so that the short-range strong force can affect them. As most common nuclear particles are positively charged, this means they must overcome considerable electrostatic repulsion before the reaction can begin. Even if the target nucleus is part of a neutral atom, the other particle must penetrate well beyond the electron cloud and closely approach the nucleus, which is positively charged. Thus, such particles must be first accelerated to high energy, for example by:
particle accelerators;
nuclear decay (alpha particles are the main type of interest here since beta and gamma rays are rarely involved in nuclear reactions);
very high temperatures, on the order of millions of degrees, producing thermonuclear reactions;
cosmic rays.

Also, since the force of repulsion is proportional to the product of the two charges, reactions between heavy nuclei are rarer, and require higher initiating energy, than those between a heavy and light nucleus; while reactions between two light nuclei are the most common ones.

Neutrons, on the other hand, have no electric charge to cause repulsion, and are able to initiate a nuclear reaction at very low energies. In fact, at extremely low particle energies (corresponding, say, to thermal equilibrium at room temperature), the neutron's de Broglie wavelength is greatly increased, possibly greatly increasing its capture cross-section, at energies close to resonances of the nuclei involved. Thus low-energy neutrons may be even more reactive than high-energy neutrons.

Notable types
While the number of possible nuclear reactions is immense, there are several types that are more common, or otherwise notable. Some examples include:
Fusion reactions — two light nuclei join to form a heavier one, with additional particles (usually protons or neutrons) emitted subsequently.
Spallation — a nucleus is hit by a particle with sufficient energy and momentum to knock out several small fragments or smash it into many fragments.
Induced gamma emission belongs to a class in which only photons were involved in creating and destroying states of nuclear excitation.
Fission reactions — a very heavy nucleus, after absorbing additional light particles (usually neutrons), splits into two or sometimes three pieces. This is an induced nuclear reaction. Spontaneous fission, which occurs without assistance of a neutron, is usually not considered a nuclear reaction. At most, it is not an induced nuclear reaction.

Direct reactions
An intermediate energy projectile transfers energy or picks up or loses nucleons to the nucleus in a single quick (10−21 second) event. Energy and momentum transfer are relatively small. These are particularly useful in experimental nuclear physics, because the reaction mechanisms are often simple enough to calculate with sufficient accuracy to probe the structure of the target nucleus.

Inelastic scattering

Only energy and momentum are transferred.
(p,p') tests differences between nuclear states.
(α,α') measures nuclear surface shapes and sizes. Since α particles that hit the nucleus react more violently, elastic and shallow inelastic α scattering are sensitive to the shapes and sizes of the targets, like light scattered from a small black object.
(e,e') is useful for probing the interior structure. Since electrons interact less strongly than do protons and neutrons, they reach to the centers of the targets and their wave functions are less distorted by passing through the nucleus.

Charge-exchange reactions
Energy and charge are transferred between projectile and target. Some examples of this kind of reactions are:

 (p,n)
 (3He,t)

Nucleon transfer reactions
Usually at moderately low energy, one or more nucleons are transferred between the projectile and target. These are useful in studying outer shell structure of nuclei. Transfer reactions can occur, from the projectile to the target; stripping reactions, or from the target to the projectile; pick-up reactions.
(α,n) and (α,p) reactions. Some of the earliest nuclear reactions studied involved an alpha particle produced by alpha decay, knocking a nucleon from a target nucleus.
(d,n) and (d,p) reactions. A deuteron beam impinges on a target; the target nuclei absorb either the neutron or proton from the deuteron. The deuteron is so loosely bound that this is almost the same as proton or neutron capture. A compound nucleus may be formed, leading to additional neutrons being emitted more slowly. (d,n) reactions are used to generate energetic neutrons.
The strangeness exchange reaction (K, π) has been used to study hypernuclei.
The reaction 14N(α,p)17O performed by Rutherford in 1917 (reported 1919), is generally regarded as the first nuclear transmutation experiment.

Reactions with neutrons

Reactions with neutrons are important in nuclear reactors and nuclear weapons. While the best-known neutron reactions are neutron scattering, neutron capture, and nuclear fission, for some light nuclei (especially odd-odd nuclei) the most probable reaction with a thermal neutron is a transfer reaction:

Some reactions are only possible with fast neutrons:
(n,2n) reactions produce small amounts of protactinium-231 and uranium-232 in the thorium cycle which is otherwise relatively free of highly radioactive actinide products.
9Be + n → 2α + 2n can contribute some additional neutrons in the beryllium neutron reflector of a nuclear weapon.
7Li + n → T + α + n unexpectedly contributed additional yield in the Bravo, Romeo and Yankee shots of Operation Castle, the three highest-yield nuclear tests conducted by the U.S.

Compound nuclear reactions
Either a low-energy projectile is absorbed or a higher energy particle transfers energy to the nucleus, leaving it with too much energy to be fully bound together. On a time scale of about 10−19 seconds, particles, usually neutrons, are "boiled" off. That is, it remains together until enough energy happens to be concentrated in one neutron to escape the mutual attraction. The excited quasi-bound nucleus is called a compound nucleus.
Low energy (e, e' xn), (γ, xn) (the xn indicating one or more neutrons), where the gamma or virtual gamma energy is near the giant dipole resonance. These increase the need for radiation shielding around electron accelerators.

See also

Acoplanarity
Atomic mass
Atomic nucleus
Atomic number
CNO cycle
Nuclear chain reaction
Oppenheimer–Phillips process
Nuclear Power

References

Sources

Physical phenomena
Nuclear chemistry
Nuclear physics
Nuclear fission
Nuclear fusion
Radioactivity

Nuclear reaction


L' Usine de produits pharmaceutiques Grandval  était une ancienne usine de produits pharmaceutiques située à Reims, en France.

Localisation
L'Usine de produits pharmaceutiques Grandval était située dans le département français de la Marne, sur la commune de Reims, 12 rue Féry.

Historique
L'usine de produits pharmaceutiques Grandval est créée, par Jean-Baptiste Grandval, en 1850 selon la date figurant sur le fronton du bâtiment situé 12 rue Féry à Reims.
Son fils Louis Alexandre poursuivra cette activité jusque vers la fin du .
Cette usine a été transformée en logements.
Le bâtiment fait l'objet d'une inscription au portail du patrimoine culturel Site Champagne-Ardenne Grand Est.

Jean-Baptiste Grandval
Jean-Baptiste Grandval (1803-1877) est né à La Houblonnière (Calvados) en 1803 et mort à Reims le 28 octobre 1877.
Chimiste et pharmacien en chef des Hospices des Reims, il fut professeur de chimie et de pharmacie à l'École de médecine de Reims.
Il est l'inventeur en 1849 d'un appareil à évaporer dans le vide qui a transformé la préparation des extraits pharmaceutiques et industriels.
Il épousa Louise Albertine Pellieux (1808-1889) avec qui il eut un fils Louis Alexandre, qui sera également pharmacien, professeur à l'École de médecine et de pharmacie de Reims, et aussi fabricant de produits chimiques en poursuivant les activités de l'Usine de produits pharmaceutiques Grandval.
Ils reposent au Cimetière du Sud de Reims.

Appareil à évaporer dans le vide
Jean-Baptiste Grandval est l'inventeur en 1849 d'un appareil à évaporer dans le vide, qui fit une révolution dans l'art de préparer les extraits pharmaceutiques et industriels.
Il fait l'objet d'un brevet d'invention de dix ans,  déposé le 21 mai 1850 et publié sous le  au bulletin des lois de la République française de 1852.

Galerie

Liens externes
https://inventaire-chalons.grandest.fr/gertrude-diffusion/recherche/globale?ou=Reims&quoi=usine+de+produits+pharmaceutiques&texte=La+Neuville-en-Tourne-%C3%A0-Fuy&typeDossier=patrimoine+industriel

Bibliographie
 Louis Alphonse Adrian, Etude historique sur les extraits pharmaceutiques, 1889, Edition Octave Doin, P109
 Bulletin des lois de la République française, 1852, P420

Références

Usine désaffectée
Urbanisme à Reims
Histoire de la pharmacie
Industrie pharmaceutique
Entreprise disparue


Haywood County er navnet på 2 counties i USA:

 Haywood County, North Carolina
 Haywood County, Tennessee

Haywood County


An Dactylorhiza incarnata in uska species han Liliopsida nga syahan ginhulagway ni Carl von Linné, ngan ginhatag han pagkayana nga asya nga ngaran ni Károly Rezsö Soó von Bere. An Dactylorhiza incarnata in nahilalakip ha genus nga Dactylorhiza, ngan familia nga Orchidaceae.

Subspecies

Ini nga species ginbahin ha masunod nga subspecies:

 D. i. coccinea
 D. i. cruenta
 D. i. gemmana
 D. i. incarnata
 D. i. lobelii
 D. i. ochroleuca
 D. i. pulchella

Mga kasarigan

Mga sumpay ha gawas

Image gallery

Dactylorhiza

Dactylorhiza incarnata


مسييه 9 هو عبارة عن عنقود كروي من النجوم يقع ضمن كوكبة الحواء، وتحديداً تقع في الجزء الجنوبي من الكوكبة إلى الجنوب الغربي من النجم إيتا أوفيوتشي على حافة البقعة المظلمة من المنطقة الضابيبة. تُسمى بيرنارد 64 .  أول من أكتشف مسييه 9 بواسطة عالم الفلك الفرنسي شارل مسييه في 3 يونيو 1764، والذي وصفه بأنه «سديم بلا نجوم». وفي عام 1783 تمكن عالم الفلك الإنجليزي ويليام هيرشل من أستخدام تلسكوبه العاكس لحل النجوم الفردية داخل العنقود. ويبلغ نصف قطر العنقود 45 سنة ضوئية. ويتحرك العنقود مبتعد عنا بسرعة عالية جداً تبلغ 224 كيلومتر / الثانية.

خصائصه
يصل القدر الظاهري للعنقود 7.7+، والحجم الزاوي 9.3، ويمكن رؤيته باستخدام تلسكوب صغير. وهي واحدة من العناقيد الكروية الأقرب إلى مركز المجرة حيث يبعد حوالي 5500 سنة ضوئية عن قلب المجرة. يبتعد عن الأرض حوالي 25,800 سنة ضوئية. ويبلغ السطوع الكلي للنعقود مسييه 9 حوالي 120,000 ضعف لمعان الشمس ويصل عدد نجوم العنقود لـ 250,000 نجم، ويبلغ القدر المطلق 8.04- ويصل القدر الظاهري لأمع نجم في العنقود إلى 13.5+ ، مما يجعله مرئي في تلسكوبات متوسطة الحجم. وتم أكتشاف 24 نجماً متغيراً في متغيرات متغيرات (RR) القيثارة، بالأضافة إلى نجوم متغير طويل المدى، والنوع متغير قيفاوي النوع الثاني، والنوع متغير الغول.

اقرأ أيضاً
 علم الفلك للأشعة السينية
 مجرة حلزونية
 نجم
 مجرة
 قزم أبيض
 عملاق أحمر
 الانفجار العظيم
 خط زمني للانفجار العظيم
 نجم نيوتروني
 ثقب أسود
 كويكبات

مراجع

أجرام الفهرس العام الجديد
أجرام فلكية اكتشفت في 1764
اكتشافات شارل مسييه
عناقيد مغلقة
فهرس مسييه
كوكبة الحواء

مسييه 9


Elisabeth Liengitz (Lingic ili Lingić), znana kao sestra Luka (Koruška, Austrija, 9. siječnja 1861. – sestrinska kuća na Betaniji, Sarajevo, 30. ožujka 1890.), redovnica Družbe Kćeri Božje ljubavi.

Rodila se u Koruškoj, kao najstarije od šestero djece poljoprivrednika Gregora i Ane Liengitz, u obitelji koja je poljskog-šleskog podrijetla, iz grada Lignica (Legnice). U 18. stoljeću u vremenu velike industrijalizacije veća je skupina Poljaka doselila i nastanila se u južnu Austriju u potrazi za boljim životom. Luka je preselila iz rodne Koruške u Beč gdje se se pridružila novoosnovanome redu Kćeri Božje ljubavi. Poglavarstvo ju je iste godine kad se zaredila poslalo u BiH, u Sarajevo. Imala je tad 22. godine. Tek nekoliko dana prije nego što je doputovala u Sarajevo položila je prve svete zavjete, 1883. godine.

Hrvatski nije znala, ali ga je naučila razgovarajući s djecom, siromašnima, starcima i bolesnicima. Djecu je kad su jutrom došla u školu u Zavod sv. Josipa prala, češljala, oblačila u toplu i čisto odjeću, a onda ih odvela u razred. U podne su ispred samostana bili siromasi čije je lončiće i zdjele punila hranom iz sestrinske kuhinje. Zvali su ju majkom sirotinje. Svim je potrebitima pomagla kako je znala i mogla. Od 1883. je sedam godina bila vrataricom u Zavodu sv. Josipa. Bila je na glasu kao iskrena moliteljica, ponizna patnica, moćna zagovornica. Umrla je na glasu svetosti kao krjeposnica 1890. od tuberkuloze, bolesti koja je nemilice zahvaćala i usmrćivala siromašno, neishranjeno ili pothranjeno stanovništvo u Austro-Ugarskoj. Pokopana je na groblju sestara Kćeri Božje ljubavi u sarajevskom naselju Betanija.

Grob joj i danas posjećuju potrebiti, bolesni i ožalošćeni, bez obzira na vjeru, dob i zanimanje. Posjetitelji mole na svoj način, kite grob, pale svijeće, preporučuju se sestri Luki ili zahvaljuju za primljeno dobro. Grob joj je danas mjestom molitve i zahvale. Štovatelji joj na grobu ostavljaju pismene molbe i zahvale za ozdravljenje, potomstvo, posao, ljubavnu sreću. Pisma se čuvaju u crkvi Kraljice sv. Krunice na Banjskom brijegu u Sarajevu.

Iščekuje se pokretanje procesa za proglašenje sestre Luke Službenicom Božjom.

Izvori

Životopisi, Sarajevo
Družba Kćeri Božje ljubavi
Katoličanstvo u Austriji
Katoličanstvo u Bosni i Hercegovini
Životopisi, Austrija

Elisabeth Luka Lingietz


Thorer Klakka era un guerrero vikingo de Noruega en el , amigo íntimo del jarl de Lade Håkon Sigurdsson. Thorer tenía larga experiencia en expediciones vikingas, algunas de ellas con fines mercantiles, por lo que estaba muy familiarizado con viajes de ultramar. En 995 Håkon había oído rumores que en los archipiélagos del norte había un tal Olaf que pregonaba su voluntad de ser rey y como por un lado sabía que Tryggve Olafsson tuvo un hijo llamado Olaf y por otro lado sospechaba que alguien con tales pretensiones debería tener vínculos con la realeza, pero no tenía certeza que fuera el mismo Olaf Tryggvason, Thorer debía esforzarse en conseguir información y usar alguna artimaña para traerlo frente al jarl. Thorer viajó hasta Dublín y encontró a Olaf junto a su cuñado Olaf Cuaran, pues Tryggvason en aquel momento estaba casado con su hermana Gytha.

Thorer logró llegar hasta Olag Tryggvason y desde el principio ambos tuvieron gran empatía, por lo que se reunieron muchas veces y hablaban de Noruega, de sus gentes y la vida en general. También le habló del jarl Håkon, un hombre de quien nadie se atreve hablar y que por su parte solo le importa oír cosas de su agrado; también que el jarl había tenido muchos problemas con el rey Harald Blåtand de Dinamarca por su oposición al Cristianismo. Olaf le preguntó su opinión personal a Thorer, particularmente si en algún momento él como pretendiente se atrevía a aparecer físicamente en Noruega. Thorer no dudaba que lograría el apoyo de los bóndi.

Olaf preparó cinco naves y partió con Thorer hacia Noruega, primero haciendo escala en las Hébridas y luego en las Orcadas. No obstante, Thorer fue testigo del verdadero temperamento, talante e intenciones del pretendiente, cuando llegó a Osmundswall, al sur de la isla Ronaldsa, donde estaba Sigurd el Fuerte, hijo de Hlodvir Thorfinnsson y tras intercambiar algunas palabras con él, le dio dos opciones: aceptar el Cristianismo y bautizarse, o morir, y detrás todas las islas a fuego y espada. Sigurd se vio forzado a aceptar, tomar juramento y ceder a uno de sus hijos como rehén y garantía de lealtad.

Referencias

Bibliografía
 Sturluson, Snorri. Heimskringla: History of the Kings of Norway, trad. Lee M. Hollander. Reprinted University of Texas Press, Austin, 1992. ISBN 0-292-73061-6

Guerreros vikingos
Vikingos de Noruega

Thorer Klakka


ශාකපොතුවට කැපීම, වලයාකාර පොතු ඉවත් කිරීම ලෙස ද හඳුන්වනු ලැබේ. මෙම ක්‍රියාවලියේදී ශාක ක‍ඳේ පොත්තන් කොටසක් කඳ වටේටම වලයාකාරව ඉවත්කරමින් (පොත්ත ද්විතීයික ෆ්ලෝයම පටකය, වල්ක කැම්බියම හා වල්කය ) ශාකය මිය යාමට සලස්වනු ලැබේ. මෙම ශාක පොතු ඉවත් කිරීම , මිනිස් ක්‍රියාකාරකම් හේතුවෙන් ( වන ව්‍යාපෘති විනාශ කිරීම් ) මෙන්ම අහම්බෙන් (ළපටි ශාක ආධාරකවලට බැඳ තබන ලණු හේතුවෙන්) හෝ සමහර ශාක භක්ෂකයන්ගේ ක්‍රියාවන් (තමන්ගේ උස ප්‍රමාණයට සරිලන ප්‍රදේශයේ ගසේ පොත්ත මුළුමණින්ම කා දැමීම) නිසා ද සිදු වේ. නමුත් මෙම උපක්‍රමය වගාවන් සඳහා වනාන්තර එළි කිරීමේදී, පලතුරු වගාකරුවන් විසින් අස්වනු වැඩිකර ගැනීම සඳහා ද බහුලව භාවිතා කෙරේ. (විශාල ඵල)

වනාන්තර පාලනයේදී හා උද්‍යාන වගාවන්වලදී පොතුවට කැපීම
සෑම ශාකයක්ම ජලය හා ආහාර පරිවහනය සඳහා සනාල පටක වර්ග 02 ක් භාවිතා කරනු ලැබේ. ඒවා නම් ශෛලම පටකය (දැව කොටස ලෙසද හඳුන්වනු ලැබේ) හා ෆ්ලෝයම පටකයයි. පොතුවට කැපීමේදී ෆ්ලෝයම පටකය පටකය ඉවත් කරනු ලබන අතර පත්‍ර මණ්ඩලවල සිට ශාකයේ මූල පද්ධතියට සීනි (මුලීකව සුක්‍රෝස් ) පරිවහනය ඇනහිටීමෙන් ශාකය මිය යාම සිදුවේ. මෙහිදී ශෛලම පටකයට කිසිදු හානියක් සිදු නොවේ. එබැවින් මූල මණ්ඩලය මිය යන තෙක් තාවකාලිකව මුල්වල සිට ගසේ පත්‍ර මණ්ඩලය වෙතට ජලය හා ඛණිජ ලවණ පරිවහනය සිදු වේ. බොහෝ විට මුල්වල සෛල තුළ තව දුරටත් ATP නිෂ්පාදනය නොවීම හේතුවෙන් හා පෝෂණ ද්‍රව්‍යය ශෛලම තුළින් ඉහළට ගමන් නොකිරීම හේතුවෙන් මූල මණ්ඩලය මිය යාම සිදු වේ.

ශාක කපා දැමීම හා සසඳන විට පොතුවට ඉවත් කිරීම මගින් ශාක ඉවත් කිරීම ඉතාමත් සෙමින් සිදුවන ක්‍රියාවලියක් බැවින් බොහෝ විට එය යොදාගනුයේ අත්‍යාවශ්‍ය අවස්ථාවකදී පමණි. එනම්, පාරිසරික සංරක්ෂිත ප්‍රදේශයක අනෙකුත් ශාකවලට හානියක් නොකර තනි ශාකයක් පමණක් ඉවත් කළයුතු අවස්ථාවලදීයි.

අහම්බයකින් ශාකයේ පොත්ත ඉවත් විය හැකි බැවින් ද ශාක කළමනාකරණයේදී ඒ පිළිබඳ සැලකිළිමත් වෙමින් ක්‍රියාකාරීවීම  වැදගත් වේ. බොහෝ විට කුඩා පැළෑටි ලණුවලින් ආධාරක කරුවලට බැඳ තැබූ විට පැළෑටිය තව දුරටත් වර්ධනය වීමේදී ලණුව සමග වන ඝර්ෂණය හේතුවෙන් එම ස්ථානයේ ක‍ඳේ පොත්ත ඉවත් වී යා හැක. එමෙන්ම කිසියම් ශාකයක නිතර නිතර සතුන් හෝ බෝට්ටු යනාදිය බැඳ තබන්නේ නම් එවිටද ඝර්ෂණය හේතුවෙන් ලණුව ඇතිල්ලෙන සීමාව තුළ ගසේ පොත්ත ඉවත් වී යා හැකිය.

ශාක පොතුවට කැපීම