Nov 16, · A method for obtaining a stable colloidal solution of silver oxide nanoparticles has been developed using laser ablation. The method allows one to obtain nanoparticles with a monomodal size distribution and a concentration of more than nanoparticles per mL. On the basis of the obtained nanoparticles and the PLGA polymer, a nanocomposite material was manufactured. The My Essay Gram: A custom essay writing service that sells original assignment help services to students. We provide essay writing services, other custom assignment help services, and research materials for references purposes only. Students should ensure that they reference the materials obtained from our website appropriately Nov 18, · The classifications and types were discussed, along with the unique properties of nanocellulose materials. Additionally, synthesis methods and methods to control properties such as size, geometric shape, and pathways to rationalize nanocellulose surface chemistry which makes it an attractive filtration material were explored
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Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respirationcan later be released to fuel the organism's activities. Most plantsalgaeand cyanobacteria perform photosynthesis; such organisms 3 unique properties of water essay called photoautotrophs.
Photosynthesis is largely responsible for producing and maintaining the oxygen content of the Earth's atmosphere, and supplies most of the energy necessary for life on Earth.
In plants, these proteins are held inside organelles called chloroplastswhich are most abundant in leaf cells, while in bacteria they are embedded in the plasma membrane.
In these light-dependent reactions, some energy is used to strip electrons from suitable substances, such as water, producing oxygen gas. The hydrogen freed by the splitting of water is used in the creation of two further compounds that serve as short-term stores of energy, enabling its transfer to drive other reactions: these compounds are reduced nicotinamide adenine dinucleotide phosphate NADPH and adenosine triphosphate ATPthe "energy currency" of cells.
In plants, algae and cyanobacteria, long-term energy storage in the form of sugars is produced by a subsequent sequence of light-independent reactions called the Calvin cycle. In the Calvin cycle, atmospheric carbon dioxide is incorporated into already existing organic carbon compounds, such as ribulose bisphosphate RuBP.
In other bacteria, different mechanisms such as the reverse Krebs cycle are used to achieve the same end. The first photosynthetic organisms probably evolved early in the evolutionary history of life and most likely used reducing agents such as hydrogen or hydrogen sulfiderather than water, as sources of electrons. Today, the average rate of energy capture by photosynthesis globally is approximately terawatts3 unique properties of water essay, [8] [9] [10] which is about eight times the current power consumption of human civilization.
Photosynthesis is vital for climate processes, as it captures carbon dioxide from the air and then binds carbon in plants and further in soils and harvested products. Cereals only are estimated to bind Tg tera grams of carbon dioxide every year, i. Photosynthetic organisms are photoautotrophswhich means that they are able to synthesize food directly from carbon dioxide and water using energy from light. However, not all organisms use carbon dioxide as a source of carbon atoms to carry out photosynthesis; photoheterotrophs use organic compounds, rather than carbon dioxide, as a source of carbon, 3 unique properties of water essay.
This is called oxygenic photosynthesis and is by far the most common type of photosynthesis used by living organisms. Although there are some differences between oxygenic photosynthesis in plantsalgaeand cyanobacteriathe overall process is quite similar in these organisms. 3 unique properties of water essay are also many varieties of anoxygenic photosynthesis3 unique properties of water essay, used mostly by certain types of bacteria, which consume carbon dioxide but do not release oxygen.
Carbon dioxide is converted into sugars in a process called carbon fixation ; photosynthesis captures energy from sunlight to convert carbon dioxide into carbohydrate. Carbon fixation is an endothermic redox reaction. In general outline, 3 unique properties of water essay, photosynthesis is the opposite of cellular respiration : while photosynthesis is a process of reduction of carbon dioxide to carbohydrate, cellular respiration is the oxidation of carbohydrate or other nutrients to carbon dioxide.
Nutrients used in cellular respiration include carbohydrates, amino acids and fatty acids. These nutrients are oxidized to produce carbon dioxide and water, and to release chemical energy to drive the organism's metabolism, 3 unique properties of water essay. Photosynthesis and cellular respiration are distinct processes, as they take place through different sequences of chemical reactions and in different cellular compartments. The general equation for photosynthesis as first proposed by Cornelis van Niel is therefore: [15].
Since water is used as the electron donor in oxygenic photosynthesis, the equation for this process is:. This equation emphasizes that water is both a reactant in the light-dependent reaction and a product of the light-independent reactionbut canceling n water molecules from each side gives the net equation:.
Other processes substitute other compounds such as arsenite for water in the electron-supply role; for example some microbes use sunlight to oxidize arsenite to arsenate : [16] The equation for this reaction is:.
Photosynthesis occurs in two stages. In the first stage, light-dependent reactions or light reactions capture the energy of light and use it to make the energy-storage molecules ATP and NADPH. During the second stage, the light-independent reactions use these products to capture and reduce carbon dioxide. Most organisms that utilize oxygenic photosynthesis use visible light for the light-dependent reactions, although at least three use shortwave infrared or, more specifically, far-red radiation.
Some organisms employ even more radical variants of photosynthesis. Some archaea use a simpler method that employs a pigment similar to those used for vision in animals. The bacteriorhodopsin changes its configuration in response to sunlight, acting as a proton pump. This produces a proton gradient more directly, which is then converted to chemical energy.
The process does not involve carbon dioxide fixation and does not release oxygen, and seems to have evolved separately from the more common types of photosynthesis. In photosynthetic bacteria, the proteins that gather light for photosynthesis are embedded in cell membranes. In its simplest form, this involves the membrane surrounding the cell itself.
In plants and algae, photosynthesis takes place in organelles called chloroplasts. A typical plant cell contains about 10 to chloroplasts. The chloroplast is enclosed by a membrane. This membrane is composed of a phospholipid inner membrane, a phospholipid outer membrane, and an intermembrane space. Enclosed by the membrane is an aqueous fluid called the stroma. Embedded within the stroma are stacks of thylakoids granawhich are the site of photosynthesis.
3 unique properties of water essay thylakoids appear as flattened disks. The 3 unique properties of water essay itself is enclosed by the thylakoid membrane, and within the enclosed volume is a lumen or thylakoid space.
Embedded in the thylakoid membrane are integral and peripheral membrane protein complexes of the photosynthetic system. Plants absorb light primarily using the pigment chlorophyll. The green part of the light spectrum is not absorbed but is reflected which is the reason that most plants have a green color. Besides chlorophyll, plants also use pigments such as carotenes and xanthophylls.
These pigments are embedded in plants and algae in complexes called 3 unique properties of water essay proteins. In such proteins, the pigments are arranged to work together.
Such a combination of proteins is also called a light-harvesting complex, 3 unique properties of water essay. Although all cells in the green parts of a plant have chloroplasts, the majority of those are found in specially adapted structures called leaves. Certain species adapted to conditions of strong sunlight and ariditysuch as many Euphorbia and cactus species, have their main photosynthetic organs in their stems.
The cells in the interior tissues of a leaf, called the mesophyllcan contain betweenandchloroplasts for every square millimeter of leaf. The surface of the leaf is coated with a water-resistant waxy cuticle that protects the leaf from excessive evaporation of water and decreases the absorption 3 unique properties of water essay ultraviolet or blue light to reduce heating.
The transparent epidermis layer allows light to pass through to the palisade mesophyll cells where most of the photosynthesis takes place. In the light-dependent reactionsone molecule of the pigment chlorophyll absorbs one photon and loses one electron. This electron is passed to a modified form of chlorophyll called pheophytinwhich passes the electron to a quinone 3 unique properties of water essay, starting the flow of electrons down an electron transport chain that leads to the ultimate reduction of NADP to NADPH.
In addition, this creates a proton gradient energy gradient across the chloroplast membranewhich is used by ATP synthase in the synthesis of ATP. The chlorophyll molecule ultimately regains the electron it lost when a water molecule is split in a process called photolysiswhich releases a dioxygen O 2 molecule as a waste product. The overall equation for the light-dependent reactions under the conditions of non-cyclic electron flow in green plants is: [26], 3 unique properties of water essay.
Not all wavelengths of light can support photosynthesis. The photosynthetic action spectrum depends on the type of accessory pigments present. For example, in green plants, the action spectrum resembles the absorption spectrum for chlorophylls and carotenoids with absorption peaks in violet-blue and red light, 3 unique properties of water essay. In red algae, the action spectrum is blue-green light, which allows these algae to use the blue end of the spectrum to grow in the deeper waters that filter out the longer wavelengths red light used by above-ground green plants.
The non-absorbed part of the light spectrum is what gives photosynthetic organisms their color e, 3 unique properties of water essay. In plants, light-dependent 3 unique properties of water essay occur in the thylakoid membranes of the chloroplasts where they 3 unique properties of water essay the synthesis of ATP and NADPH. The light-dependent reactions are of two forms: cyclic and non-cyclic.
In the non-cyclic reaction, the photons are captured in the light-harvesting antenna complexes of photosystem II by chlorophyll and other accessory pigments see diagram at right.
The absorption of a photon by the antenna complex frees an electron by a process called photoinduced charge separation. The antenna system is at the core of the chlorophyll molecule of the photosystem II reaction center. That freed electron is transferred to the primary electron-acceptor molecule, 3 unique properties of water essay, pheophytin.
An ATP synthase enzyme uses that chemiosmotic potential to make ATP during photophosphorylationwhereas NADPH is a product of the terminal redox reaction in the Z-scheme. The electron enters a chlorophyll molecule in Photosystem I.
There it is further excited by the light absorbed by that photosystem. The electron is then passed along a chain of electron acceptors to which it transfers some of its energy. The energy delivered to the electron acceptors is used to move hydrogen ions across the thylakoid membrane into the lumen. The cyclic reaction is similar to that of the non-cyclic but differs in that it generates only ATP, and no reduced NADP NADPH is created.
The cyclic reaction takes place only at photosystem I. Once the electron is displaced from the photosystem, the electron is passed down the electron acceptor molecules and returns to photosystem I, from where it was emitted, hence the name cyclic reaction. Linear electron transport through a photosystem will leave the reaction center of that photosystem oxidized. Elevating another electron will first require re-reduction of the reaction center.
The excited electrons lost from the reaction center P of photosystem I are replaced by transfer from plastocyaninwhose electrons come from electron transport through photosystem II. Photosystem II, as the first step of the Z-schemerequires an external source of electrons to reduce its oxidized chlorophyll a reaction center, called P The source of electrons for photosynthesis in green plants and cyanobacteria is water. Two water molecules are oxidized by four successive charge-separation reactions by photosystem II to yield a molecule of diatomic oxygen and four hydrogen ions.
The electrons yielded are transferred to a redox-active tyrosine residue that then reduces the oxidized P This resets the ability of P to absorb another photon and release another photo-dissociated electron.
The oxidation of water is catalyzed in photosystem II by a redox-active structure that contains four manganese ions and a calcium ion; this oxygen-evolving complex binds two water molecules and contains the four oxidizing equivalents that are used to drive the water-oxidizing reaction Dolai's S-state diagrams. Photosystem II is the only known biological enzyme that carries out this oxidation of water. The hydrogen ions are released in the thylakoid lumen and therefore contribute to the transmembrane chemiosmotic potential that leads to ATP synthesis.
Oxygen is a waste product of light-dependent reactions, but the majority of organisms on Earth use oxygen for cellular respirationincluding photosynthetic organisms. In the light-independent or "dark" reactions, the enzyme RuBisCO captures CO 2 from the atmosphere and, in a process called the Calvin cycleit uses the newly formed NADPH and releases three-carbon sugars, which are later combined to form sucrose and starch.
Carbon fixation produces the intermediate three-carbon sugar product, which is then converted into the final carbohydrate products. The simple carbon sugars produced by photosynthesis are then used in the forming of other organic compounds, such as the building material cellulosethe precursors for lipid and amino acid biosynthesis, or as a fuel in cellular respiration.
The latter occurs not only in plants but also in animals when the energy from plants is passed through a food chain.
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, time: 3:05Arthur Schopenhauer (Stanford Encyclopedia of Philosophy)
Essay Fountain: A custom essay writing service that sells original assignment help services to students. We provide essay writing services, other custom assignment help services, and research materials for references purposes only. Students should ensure that they reference the materials obtained from our website appropriately Oct 16, · In a stochastic model, current state does not dictate a unique next state. Rather, there is a certain probability that the machine will transition from one state to another. CCTM claims that mental activity is “Turing-style computation”, allowing these and other departures from Turing’s own formalism. Machine functionalism Apr 09, · How to write an essay for UC Prompt 5: Complete the Feelings and Needs Exercise. Decide what the “chunks” of your essay are. One simple way to do this is to use the Challenges/What I did/What I Learned structure. Use the questions in the outline above to expand from the 3“chunks” (i.e., paragraphs or “scenes” in your story) to 5
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