Friday, July 25, 2014
The amazing dual behaviour of hydrogen.
HYDROGEN COMPOUNDS
Hydrogen in atomic form consist of one proton and one electron but , in elemental form it exists as a atomic ( H2 ) molecule . H2 is called as dihydrogen.
Position of hydrogen in the periodic table : Hydrogen is the first element of the periodic table as its atomic number is 1 . The single electron is present in the K shell i.e 1s1
The real growth in Neuroscience
Neuroscience is advancing rapidly. Nobody's questioning that. Brain-computer interfaces, optogenetics, transcranial magnetic stimulation—there's a lot of good stuff out there.
With respect to applications, a gaggle of neurotechnology startups are already starting to chip away at some curious corners of the medical technology space. But is the market ready? And more importantl y, is the science ready? This piece gives us some relatively concrete projection s on market readiness and financial/ scientific feasibility for a handful of emerging technologi es .
I'm a bit more conservat ive than the authors, though. Mainstrea m optogene tic implants in humans by 2026? Even if neuroscie nce does manage to wrangle $4.5 billion in extra funding over the next twelve years, I don't see this happenin g.
{
Optogenetic implants in humans: The combination of genetic and optical methods to control specific events in targeted cells of living tissue, even within freely moving mammals and other animals, with the temporal precision (millisecond timescale) needed to keep pace with functioning intact biological systems.
Scientifically viable in 2021; mainstream and financially viable in 2026.
Really very hot stuff : Pepper
You know that tingling, numbing sensation you get from Sichuan peppers? It turns out that 'tingling' and 'numbing' might actually be the best way to describe it. A series of recent studies has shown that the relevant ingredient in the peppers targets neurons that respond to touch and vibration, thereby triggering the buzzing perception.
What's more is that evidence suggests we all feel those tingling vibrations at the same frequency. (It's around a low G.)
If only science was always this spicy.
{
The task for the tingling volunteers was to try to match the peppery vibrations in their mouths to the vibrations they could feel in their fingertips as the researchers dialed the frequency of the box up or down — "They are closing their eyes and they're saying 'higher' or 'lower,' so it's kind of a bizarre situation," says Hagura — until the Sichuan buzz and the mechanical buzz converged on the same frequency, which turns out to be 50 hertz.Thursday, July 24, 2014
NASA X-43A 'Scramjet' Readied For Mach 10 Flight
NASA's high-risk, high-payoff Hyper-X Program is ready to attempt its greatest challenge yet - flying a "scramjet"-powered X-43A research vehicle at nearly 10 times the speed of sound.
Officials have set Nov. 15 or 16 for the flight, which will take place in restricted U.S. Naval airspace over the Pacific Ocean northwest of Los Angeles.
GaneshScience: s-BLOCK ELEMENTS
GaneshScience: s-BLOCK ELEMENTS: custom toolbar custom toolbar S.No. Atomic Properties Alkali metal 1. Outer electronic configuration ns^1 2. Oxidation nu...
Anti-Evolutionist s Need to Stop Talking About thermodynamics
The anti-evolutionists just never get tired of the second law thermodynamics! The latest bit of silliness comes from Barry Arrington, writing at Uncommon Descent. Here’s the whole post:
I hope our materialist friends will help us with this one.
As I understand their argument, entropy is not an obstacle to blind watchmaker evolution, because entropy applies absolutely only in a “closed system,” and the earth is not a closed system because it receives electromagnetic radiation from space.
Fair enough. But it seems to me that under that definition of “closed system” only the universe as a whole is a closed system, because every particular place in the universe receives energy of some kind from some other place. And if that is so, it seems the materialists have painted themselves into a corner in which they must, to remain logically consistent, assert that entropy applies everywhere but no place in particular, which is absurd.
Now this seems like an obvious objection, and if it were valid the “closed system/open system” argument would have never gained any traction to begin with. So I hope someone will clue me in as to what I am missing.
I think Arrington is missing quite a lot, actually.
Let’s start with the obvious. Many physical laws and theories only strictly apply to idealized scenarios, but that does not stop them from being very useful. There are no ideal gases in nature, but we have an ideal gas law that tells us how they behave. Physical objects never engage in perfectly elastic collisions, but classical mechanics tells us quite a lot about what would happen if they did. Heck, there are no triangles in nature, but trigonometry is still fantastically useful stuff.
So, yes, the only truly closed system is the universe as a whole, a fact pointed out in virtually every book on thermodynamics. But there are many systems that are close enough to closed for practical purposes, and that is enough to make the second law very useful indeed.
(Incidentally, for the purposes of this post I won’t belabor the distinction between a closed system and an isolated system. The former refers to one where no mass is crossing the system’s boundary, while the latter requires that neither matter nor energy is crossing the boundary. If you are making the statement, “Entropy cannot spontaneously decrease,” then you had better be talking about an isolated system. While we’re at it, for the purposes of this post I will be discussing everything in the context of classical thermodynamics. I will not discuss statistical mechanics or anything like that.)
The bigger thing that Arrington is missing, however, is that there is so much more to the second law than the statement that entropy cannot decrease in an isolated system.
One frustration in learning about thermodynamics is that you can consult a multitude of textbooks and popularizations and never find the second law stated the same way twice. Sometimes it is boiled down to the simple statement that heat always travels from a hot body to a cooler body. Sometimes it is expressed in terms of heat engines. Sometimes it is presented with an impenetrable amount of mathematics. Making things worse is that it is very hard to pin down what, precisely, entropy is. That’s why you get a lot of talk about complexity, or randomness, or useful energy, in popularizations of this topic. These ideas capture some of the spirit of the concept, but they also fool a lot of people into thinking they know what they are talking about.
When creationists first noticed that the second law could be used to rhetorical advantage, they tended to do so in a shockingly naïve way. For example, here’s Henry Morris, from his bookThe Troubled Waters of Evolution:
Evolutionists have fostered the strange belief that everything is involved in a process of progress, from chaotic particles billions of years ago all the way up to complex people today. The fact is, the most certain laws of science state that the real processes of nature do not make things go uphill, but downhill. Evolution is impossible!
And later:
There is … firm evidence that evolution never could take place.The law of increasing entropyis an impenetrable barrier which no evolutionary mechanism yet suggested has ever been able to overcome. Evolution and entropy are opposing and mutually exclusive concepts. If the entropy principle is really a universal law, then evolution must be impossible.
Now, when creationists are saying things likethat, it is perfectly reasonable to emphasize in reply that the second law only precludes spontaneous decreases in entropy in isolated systems, which the Earth certainly is not. But that statement is hardly the entirety of what physicists know about entropy.
To fully understand the magnitude of what Arrington is missing, we should consider what the second law was accomplishes. The principles of thermodynamics make certain claims about what sorts of processes are physically possible.
Super-sniffing elephants
Super-sniffing elephants
Feral Cats as Invasive Species
The ranger stood on the dirt road, facing south, and the rest of us, scattered about the parked safari truck, facing north and paying close attention to what she was saying. The sun was slipping quickly below the red sand dunes to our west, and the day’s warm breeze was rapidly changing to a chill wind. She talked about what we might see after we remounted the safari truck, which we had just driven out of the campground at the southern end of Kgalgadi Transfrontier Park, where we were staying in the South African camp, just across from the Botswana camp. This would be a night drive, cold, dark, uncomfortable seats, loud engine in the giant 26-seater truck, scanning the brush and the roadside with three or four strong spotlights wrangled by volunteers among the nature-loving tourists, and of course, the headlights of the truck. But for now the sun was still up and if anything interesting came along we’d see it just fine in the dusk.
And, of course, something interesting came along. Just as the ranger was telling us that we might see wild cats – well, not wild cats, but rather, Wildcats, the wild version of the domestic cat, Felis silvestris lybica, one of those cats popped its head out of the brush about 50 feet beyond her. As she continued her monologue about these cats, the Wildcat cautiously walked in our direction, never taking its eyes off of us, stiff-legged, ears motionless, striped like a standard “tiger” domestic cat but entirely in grays. The most interesting thing about this cat was lack of kitty-cat-ness. It was not a kitty cat, even though all of its relatives in the Americas were. It was deadly serious, intense looking, nothing like a kitty cat at all. And just as the ranger finished her monologue with “… so if we’re lucky, we’ll see one of those cats” the person standing next to me intoned, in a mimicking fake british-sounding accent to match the ranger’s South African dialect, “You mean like that one, there?” and all of us pointed simultaneously to the wildcat now about 10 feet behind her.
She turned, looked, and by the expression on her face I guessed she was thinking “Goodness, I’m glad that was not a lion.”
Protein : Other info
Methods of study
Main article: Protein methods
The activities and structures of proteins may be examined in vitro, in vivo, and in silico.In vitrostudies of purified proteins in controlled environments are useful for learning how a protein carries out its function: for example, enzyme kineticsstudies explore the chemical mechanismof an enzyme's catalytic activity and its relative affinity for various possible substrate molecules. By contrast,in vivoexperiments can provide information about the physiological role of a protein in the context of a cellor even a whole organism.In silicostudies use computational methods to study proteins.
Protein purification
Main article: Protein purification
To perform in vitroanalysis, a protein must be purified away from other cellular components. This process usually begins with cell lysis, in which a cell's membrane is disrupted and its internal contents released into a solution known as a crude lysate. The resulting mixture can be purified using ultracentrifugation, which fractionates the various cellular components into fractions containing soluble proteins; membrane lipidsand proteins; cellular organelles, and nucleic acids. Precipitationby a method known as salting outcan concentrate the proteins from this lysate. Various types of chromatographyare then used to isolate the protein or proteins of interest based on properties such as molecular weight, net charge and binding affinity. [ 38 ]The level of purification can be monitored using various types of gel electrophoresisif the desired protein's molecular weight and isoelectric pointare known, by spectroscopyif the protein has distinguishable spectroscopic features, or by enzyme assaysif the protein has enzymatic activity. Additionally, proteins can be isolated according their charge using electrofocusing. [ 39 ]
For natural proteins, a series of purification steps may be necessary to obtain protein sufficiently pure for laboratory applications. To simplify this process, genetic engineeringis often used to add chemical features to proteins that make them easier to purify without affecting their structure or activity. Here, a "tag" consisting of a specific amino acid sequence, often a series of histidineresidues (a " His-tag"), is attached to one terminus of the protein. As a result, when the lysate is passed over a chromatography column containing nickel, the histidine residues ligate the nickel and attach to the column while the untagged components of the lysate pass unimpeded. A number of different tags have been developed to help researchers purify specific proteins from complex mixtures. [ 40 ]
Cellular localization
Proteins in different cellular compartmentsand structures tagged with green fluorescent protein(here, white)
The study of proteinsin vivois often concerned with the synthesis and localization of the protein within the cell. Although many intracellular proteins are synthesized in the cytoplasmand membrane-bound or secreted proteins in the endoplasmic reticulum, the specifics of how proteins are targetedto specific organelles or cellular structures is often unclear. A useful technique for assessing cellular localization uses genetic engineering to express in a cell a fusion proteinor chimeraconsisting of the natural protein of interest linked to a " reporter" such as green fluorescent protein(GFP). [ 41 ]The fused protein's position within the cell can be cleanly and efficiently visualized using microscopy, [ 42 ]as shown in the figure opposite.
Other methods for elucidating the cellular location of proteins requires the use of known compartmental markers for regions such as the ER, the Golgi, lysosomes or vacuoles, mitochondria, chloroplasts, plasma membrane, etc. With the use of fluorescently tagged versions of these markers or of antibodies to known markers, it becomes much simpler to identify the localization of a protein of interest. For example, indirect immunofluorescencewill allow for fluorescence colocalization and demonstration of location. Fluorescent dyes are used to label cellular compartments for a similar purpose. [ 43 ]
Other possibilities exist, as well. For example, immunohistochemistryusually utilizes an antibody to one or more proteins of interest that are conjugated to enzymes yielding either luminescent or chromogenic signals that can be compared between samples, allowing for localization information. Another applicable technique is cofractionation in sucrose (or other material) gradients using isopycnic centrifugation. [ 44 ]While this technique does not prove colocalization of a compartment of known density and the protein of interest, it does increase the likelihood, and is more amenable to large-scale studies.
Finally, the gold-standard method of cellular localization is immunoelectron microscopy. This technique also uses an antibody to the protein of interest, along with classical electron microscopy techniques.
Structural protein
Structural proteins
Structural proteins confer stiffness and rigidity to otherwise-fluid biological components. Most structural proteins are fibrous proteins; for example, collagenand elastinare critical components of connective tissuesuch as cartilage, and keratinis found in hard or filamentous structures such as hair, nails, feathers, hooves, and some animal shells. [ 36 ]Some globular proteinscan also play structural functions, for example, actinand tubulinare globular and soluble as monomers, but polymerizeto form long, stiff fibers that make up the cytoskeleton, which allows the cell to maintain its shape and size.
Other proteins that serve structural functions are motor proteinssuch as myosin, kinesin, and dynein, which are capable of generating mechanical forces. These proteins are crucial for cellular motilityof single celled organisms and the spermof many multicellular organisms which reproduce sexually. They also generate the forces exerted by contracting muscles [ 37 ]and play essential roles in intracellular transport.
Main Role of protein in body.
Types of synthesis : 2. Chemical synthesis
Chemical synthesis
Short proteins can also be synthesized chemically by a family of methods known as peptide synthesis, which rely on organic synthesistechniques such as chemical ligationto produce peptides in high yield. [ 9 ]Chemical synthesis allows for the introduction of non-natural amino acids into polypeptide chains, such as attachment of fluorescentprobes to amino acid side chains. [ 10 ]These methods are useful in laboratory biochemistryand cell biology, though generally not for commercial applications. Chemical synthesis is inefficient for polypeptides longer than about 300 amino acids, and the synthesized proteins may not readily assume their native tertiary structure. Most chemical synthesis methods proceed from C-terminus to N-terminus, opposite the biological reaction. [ 11 ]
Structure
Main article: Protein structure
Further information: Protein structure prediction
The crystal structure of the chaperonin. Chaperonins assist protein folding.
Three possible representations of the three-dimensional structure of the protein triose phosphate isomerase. Left: all-atom representation colored by atom type. Middle: Simplified representation illustrating the backbone conformation, colored by secondary structure. Right: Solvent-accessible surface representation colored by residue type (acidic residues red, basic residues blue, polar residues green, nonpolar residues white)
Most proteins foldinto unique 3-dimensional structures. The shape into which a protein naturally folds is known as its native conformation. [ 12 ]Although many proteins can fold unassisted, simply through the chemical properties of their amino acids, others require the aid of molecular chaperonesto fold into their native states. [ 13 ]Biochemists often refer to four distinct aspects of a protein's structure: [ 14 ]
*. Primary structure: the amino acid sequence. A protein is a polyamide.
*. Secondary structure: regularly repeating local structures stabilized by hydrogen bonds. The most common examples are the alpha helix, beta sheetand turns. Because secondary structures are local, many regions of different secondary structure can be present in the same protein molecule.
*. Tertiary structure: the overall shape of a single protein molecule; the spatial relationship of the secondary structures to one another. Tertiary structure is generally stabilized by nonlocal interactions, most commonly the formation of a hydrophobic core, but also through salt bridges, hydrogen bonds, disulfide bonds, and even posttranslational modifications. The term "tertiary structure" is often used as synonymous with the termfold. The tertiary structure is what controls the basic function of the protein.
*. Quaternary structure: the structure formed by several protein molecules (polypeptide chains), usually called protein subunitsin this context, which function as a single protein complex.
Proteins are not entirely rigid molecules. In addition to these levels of structure, proteins may shift between several related structures while they perform their functions. In the context of these functional rearrangements, these tertiary or quaternary structures are usually referred to as " conformations", and transitions between them are calledconformational changes.Such changes are often induced by the binding of a substratemolecule to an enzyme's active site, or the physical region of the protein that participates in chemical catalysis. In solution proteins also undergo variation in structure through thermal vibration and the collision with other molecules. [ 15 ]
Molecular surface of several proteins showing their comparative sizes. From left to right are: immunoglobulin G(IgG, an antibody), hemoglobin, insulin(a hormone), adenylate kinase(an enzyme), and glutamine synthetase(an enzyme).
Proteins can be informally divided into three main classes, which correlate with typical tertiary structures: globular proteins, fibrous proteins, and membrane proteins. Almost all globular proteins are solubleand many are enzymes. Fibrous proteins are often structural, such as collagen, the major component of connective tissue, or keratin, the protein component of hair and nails. Membrane proteins often serve as receptorsor provide channels for polar or charged molecules to pass through the cell membrane. [ 16 ]
A special case of intramolecular hydrogen bonds within proteins, poorly shielded from water attack and hence promoting their own dehydration, are called dehydrons.
Types of Protein synthesis 1) Biosynthesis
Synthesis
Biosynthesis
Main article: Protein biosynthesis
A ribosome produces a protein using mRNA as template.
The DNAsequence of a gene encodesthe amino acidsequence of a protein.
Proteins are assembled from amino acids using information encoded in genes. Each protein has its own unique amino acid sequence that is specified by the nucleotidesequence of the gene encoding this protein. The genetic codeis a set of three-nucleotide sets called codonsand each three-nucleotide combination designates an amino acid, for example AUG ( adenine- uracil- guanine) is the code for methionine. Because DNAcontains four nucleotides, the total number of possible codons is 64; hence, there is some redundancy in the genetic code, with some amino acids specified by more than one codon. [ 6 ]Genes encoded in DNA are first transcribedinto pre- messenger RNA(mRNA) by proteins such as RNA polymerase. Most organisms then process the pre-mRNA (also known as aprimary transcript) using various forms of Post-transcriptional modificationto form the mature mRNA, which is then used as a template for protein synthesis by the ribosome. In prokaryotesthe mRNA may either be used as soon as it is produced, or be bound by a ribosome after having moved away from the nucleoid. In contrast, eukaryotesmake mRNA in the cell nucleusand then translocateit across the nuclear membraneinto the cytoplasm, where protein synthesisthen takes place. The rate of protein synthesis is higher in prokaryotes than eukaryotes and can reach up to 20 amino acids per second. [ 7 ]
The process of synthesizing a protein from an mRNA template is known as translation. The mRNA is loaded onto the ribosome and is read three nucleotides at a time by matching each codon to its base pairing anticodonlocated on a transfer RNAmolecule, which carries the amino acid corresponding to the codon it recognizes. The enzyme aminoacyl tRNA synthetase"charges" the tRNA molecules with the correct amino acids. The growing polypeptide is often termed thenascent chain. Proteins are always biosynthesized from N-terminusto C-terminus. [ 6 ]
The size of a synthesized protein can be measured by the number of amino acids it contains and by its total molecular mass, which is normally reported in units ofdaltons(synonymous with atomic mass units), or the derivative unit kilodalton (kDa). Yeastproteins are on average 466 amino acids long and 53 kDa in mass. [ 5 ]The largest known proteins are the titins, a component of the muscle sarcomere, with a molecular mass of almost 3,000 kDa and a total length of almost 27,000 amino acids.
Biochemestry protein : Most interesting topic of the day
Most proteins consist of linear polymersbuilt from series of up to 20 differentL-α- amino acids. All proteinogenic amino acidspossess common structural features, including an α-carbonto which an aminogroup, a carboxylgroup, and a variable side chainare bonded. Only prolinediffers from this basic structure as it contains an unusual ring to the N-end amine group, which forces the CO–NH amide moiety into a fixed conformation. [ 1 ]The side chains of the standard amino acids, detailed in the list of standard amino acids, have a great variety of chemical structures and properties; it is the combined effect of all of the amino acid side chains in a protein that ultimately determines its three-dimensional structure and its chemical reactivity. [ 2 ]The amino acidsin a polypeptide chain are linked by peptide bonds. Once linked in the protein chain, an individual amino acid is called aresidue,and the linked series of carbon, nitrogen, and oxygen atoms are known as themain chainorprotein backbone. [ 3 ]
The peptide bond has two resonanceforms that contribute some double-bondcharacter and inhibit rotation around its axis, so that the alpha carbons are roughly coplanar. The other two dihedral anglesin the peptide bond determine the local shape assumed by the protein backbone. [ 4 ]The end of the protein with a free carboxyl group is known as the C-terminusor carboxy terminus, whereas the end with a free amino group is known as the N-terminusor amino terminus. The wordsprotein,polypeptide,and peptideare a little ambiguous and can overlap in meaning.Proteinis generally used to refer to the complete biological molecule in a stable conformation, whereaspeptideis generally reserved for a short amino acid oligomers often lacking a stable three-dimensional structure. However, the boundary between the two is not well defined and usually lies near 20–30 residues. [ 5 ]Polypeptidecan refer to any single linear chain of amino acids, usually regardless of length, but often implies an absence of a defined conformation.
Protein
Proteins( / ˈ p r oʊ ˌ t iː n z /or / ˈ p r oʊ t i . ɨ n z /) are large biological molecules, or macromolecules, consisting of one or more long chains of amino acid residues. Proteins perform a vast array of functions within living organisms, including catalyzing metabolic reactions, replicating DNA, responding to stimuli, and transporting molecules from one location to another. Proteins differ from one another primarily in their sequence of amino acids, which is dictated by the nucleotide sequenceof their genes, and which usually results in foldingof the protein into a specific three- dimensional structurethat determines its activity.
A linear chain of amino acid residues is called a polypeptide. A protein contains at least one long polypeptide. Short polypeptides, containing less than about 20-30 residues, are rarely considered to be proteins and are commonly called peptides, or sometimes oligopeptides. The individual amino acid residues are bonded together by peptide bondsand adjacent amino acid residues. The sequenceof amino acid residues in a protein is defined by the sequenceof a gene, which is encoded in the genetic code. In general, the genetic code specifies 20 standard amino acids; however, in certain organisms the genetic code can include selenocysteineand—in certain archaea— pyrrolysine. Shortly after or even during synthesis, the residues in a protein are often chemically modified by posttranslational modification, which alters the physical and chemical properties, folding, stability, activity, and ultimately, the function of the proteins. Sometimes proteins have non-peptide groups attached, which can be called prosthetic groupsor cofactors. Proteins can also work together to achieve a particular function, and they often associate to form stable protein complexes.
Once formed, proteins only exist for a certain period of time and are then degradedand recycled by the cell's machinery through the process of protein turnover. A protein's lifespan is measured in terms of its half-lifeand covers a wide range. They can exist for minutes or years with an average lifespan of 1-2 days in mammalian cells. Abnormal and or misfolded proteins are degraded more rapidly either due to being targeted for destruction or due to being unstable.
Like other biological macromoleculessuch as polysaccharidesand nucleic acids, proteins are essential parts of organisms and participate in virtually every process within cells. Many proteins are enzymesthat catalyzebiochemical reactions and are vital to metabolism. Proteins also have structural or mechanical functions, such as actinand myosinin muscle and the proteins in the cytoskeleton, which form a system of scaffoldingthat maintains cell shape. Other proteins are important in cell signaling, immune responses, cell adhesion, and the cell cycle. Proteins are also necessary in animals' diets, since animals cannot synthesizeall the amino acids they need and must obtain essential amino acidsfrom food. Through the process of digestion, animals break down ingested protein into free amino acids that are then used in metabolism.
Proteins may be purifiedfrom other cellular components using a variety of techniques such as ultracentrifugation, precipitation, electrophoresis, and chromatography; the advent of genetic engineeringhas made possible a number of methods to facilitate purification. Methods commonly used to study protein structure and function include immunohistochemistry, site-directed mutagenesis, X-ray crystallography, nuclear magnetic resonanceand mass spectrometry.
Atmospheric Pressure
CONVERVATION OF BIODIVERSITY AND ENVIRONMENT
Biological diversity.
Tissue Culture
Tissue Culture
STARS AND OUR SOLAR SYSTEM
CO2 (Carbon Dioxide) for Good Use.
Soil Pollution
Microbial fuel cell new
Amicrobial fuel cell(MFC) orbiological fuel cellis a bio- electrochemicalsystem that drives a currentby usingbacteria and mimicki ... bacteriaand mimicking bacterial interactions found in nature. MFCs can be grouped into two general categories, those that use a mediator and those that are mediator-less. The first MFCs, demonstrated in the early 20th century, used a mediator: a chemical that transfers electrons from the bacteria in the cell to the anode. Mediator-less MFCs are a more recent development dating to the 1970s; in this type of MFC the bacteria typically have electrochemically active redox proteinssuch as cytochromeson their outer membrane that can transfer electrons directly to the anode. [ 1 ]Since the turn of the 21st century MFCs have started to find a commercial use in the treatment of wastewater. [ 2 ]
History
The idea of using microbial cells in an attempt to produce electricitywas first conceived in the early twentieth century. M. Potter was the first to perform work on the subject in 1911. [ 3 ]A professor of botany at the University of Durham, Potter managed to generate electricity from E. coli, but the work was not to receive any major coverage. In 1931, however, Barnet Cohen drew more attention to the area when he created a number of microbial half fuel cells that, when connected in series, were capable of producing over 35 volts, though only with a current of 2 milliamps. [ 4 ]
More work on the subject came with a study by DelDuca et al. who used hydrogen produced by the fermentationof glucose by Clostridium butyricumas the reactant at the anode of a hydrogen and air fuel cell. Though the cell functioned, it was found to be unreliable owing to the unstable nature of hydrogen production by the micro-organisms. [ 5 ]Although this issue was later resolved in work by Suzuki et al. in 1976 [ 6 ]the current design concept of an MFC came into existence a year later with work once again by Suzuki. [ 7 ]
By the time of Suzuki’s work in the late 1970s, little was understood about how microbial fuel cells functioned; however, the idea was picked up and studied later in more detail first by MJ Allen and then later by H. Peter Bennetto both from King's College London. People saw the fuel cell as a possible method for the generation of electricity for developing countries. His work, starting in the early 1980s, helped build an understanding of how fuel cells operate, and until his retirement, he was seen by many[ who?]as the foremost authority on the subject.
It is now known that electricity can be produced directly from the degradation of organic matter in a microbial fuel cell. Like a normal fuel cell, an MFC has both an anode and a cathode chamber. The anoxicanode chamber is connected internally to the cathode chamber via an ion exchange membrane with the circuit completed by an external wire.
In May 2007, the University of Queensland, Australia completed its prototype MFC as a cooperative effort with Foster's Brewing. The prototype, a 10 L design, converts brewery wastewaterinto carbon dioxide, clean water, and electricity. With the prototype proven successful[ citation needed], plans are in effect to produce a 660 gallon version for the brewery, which is estimated to produce 2 kilowatts of power. While this is a small amount of power, the production of clean water is of utmost importance to Australia, for which droughtis a constant threat.
Organic Chemestry
Organic chemistryis a chemistrysubdiscipline involving the scientificstudy of the structure, properties, and reactions of organic compoundsand organic materials, i.e., matter in its various forms that contain carbon atoms. [ 1 ]Study of structure includes using spectroscopy (e.g., NMR), mass spectrometry, and other physical and chemical methods to determine the chemical compositionand constitutionof organic compounds and materials. Study of properties includes both physical propertiesand chemical properties, and uses similar methods as well as methods to evaluate chemical reactivity, with the aim to understand the behavior of the organic matter in its pure form (when possible), but also in solutions, mixtures, and fabricated forms. The study of organic reactionsincludes probing their scope through use in preparation of target compounds (e.g., natural products, drugs, polymers, etc.) by chemical synthesis, as well as the focused study of the reactivitiesof individual organic molecules, both in the laboratory and via theoretical ( in silico) study.
The range of chemicals studied in organic chemistry include hydrocarbons, compounds containing only carbonand hydrogen, as well as myriad compositions based always on carbon, but also containing other elements, [ 1 ] [ 2 ] [ 3 ]especially:
*.oxygen, nitrogen, sulfur, phosphorus (these, included in many organic chemicals in biology) and the radiostableof the halogens.
In the modern era, the range extends further into the periodic table, with main group elements, including:
*.Group 1 and 2 organometallic compounds, i.e., involving alkali(e.g., lithium, sodium, and potassium) or alkaline earth metals(e.g., magnesium), or
*. metalloids(e.g., boron and silicon) or other metals(e.g., aluminum and tin).
In addition, much modern research focuses on organic chemistry involving further organometallics, including the lanthanides, but especially the:
*. transition metals(e.g., zinc, copper, palladium, nickel, cobalt, titanium, chromium, etc.).
Line-angle representation
Ball-and-stick representation
Space-filling representation
Three representations of an organic compound, 5α-Dihydroprogesterone(5α-DHP), a steroid hormone. For molecules showing color, the carbon atoms are in black, hydrogens in gray, and oxygens in red. In the line angle representation, carbon atoms are implied at every terminus of a line and vertex of multiple lines, and hydrogen atoms are implied to fill the remaining needed valences (up to 4).
Finally, organic compoundsform the basis of all earthly lifeand constitute a significant part of human endeavors in chemistry. The bonding patterns open to carbon, with its valence of four—formal single, double, and triple bonds, as well as various structures with delocalized electrons—make the array of organic compounds structurally diverse, and their range of applications enormous. They either form the basis of, or are important constituents of, many commercial products including pharmaceuticals; petrochemicalsand products made from them (including lubricants, solvents, etc.); plastics; fuelsand explosives; etc. As indicated, the study of organic chemistry overlaps with organometallic chemistryand biochemistry, but also with medicinal chemistry, polymer chemistry, as well as many aspects of materials science. [ 1 ]
Periodic tableof elements of interest in organic chemistry. The table illustrates all elementsof current interest in modern organic and organometallicchemistry, indicating main group elementsin orange, and transition metalsand lanthanides(Lan) in grey.
Inorganic Chemestry
Inorganic chemistryis the study of the synthesis and behavior of inorganic and organometallic compounds. This field covers all chemical compoundsexcept the myriad organic compounds(carbon based compounds, usually containing C-H bonds), which are the subjects of organic chemistry. The distinction between the two disciplines is far from absolute, and there is much overlap, most importantly in the sub-discipline of organometallic chemistry. It has applications in every aspect of the chemical industry–including catalysis, materials science, pigments, surfactants, coatings, medicine, fuel, and agriculture. [ 1 ]
Key concepts
The structure of the ionic framework in potassium oxide, K2O
Many inorganic compoundsare ionic compounds, consisting of cationsand anionsjoined by ionic bonding. Examples of salts (which are ionic compounds) are magnesium chlorideMgCl2, which consists of magnesiumcations Mg2+and chlorideanions Cl−; or sodium oxideNa2O, which consists of sodiumcations Na+and oxideanions O2−. In any salt, the proportions of the ions are such that the electric charges cancel out, so that the bulk compound is electrically neutral. The ions are described by their oxidation stateand their ease of formation can be inferred from the ionization potential(for cations) or from the electron affinity(anions) of the parent elements.
Important classes of inorganic salts are the oxides, the carbonates, the sulfatesand the halides. Many inorganic compounds are characterized by high melting points. Inorganic salts typically are poor conductorsin the solid state. Other important features include their solubility in water(see: solubility chart) and ease of crystallization. Where some salts (e.g., NaCl) are very soluble in water, others (e.g., SiO 2) are not.
The simplest inorganic reactionis double displacementwhen in mixing of two salts the ions are swapped without a change in oxidation state. In redox reactionsone reactant, theoxidant, lowers its oxidation state and another reactant, thereductant, has its oxidation state increased. The net result is an exchange of electrons. Electron exchange can occur indirectly as well, e.g., in batteries, a key concept in electrochemistry.
When one reactant contains hydrogen atoms, a reaction can take place by exchanging protons in acid-base chemistry. In a more general definition, an acid can be any chemical species capable of binding to electron pairs is called a Lewis acid; conversely any molecule that tends to donate an electron pair is referred to as a Lewis base. As a refinement of acid-base interactions, the HSAB theorytakes into account polarizability and size of ions.
Inorganic compounds are found in nature as minerals. Soil may contain iron sulfide as pyriteor calcium sulfate as gypsum. Inorganic compounds are also found multitasking as biomolecules: as electrolytes ( sodium chloride), in energy storage ( ATP) or in construction (the polyphosphatebackbone in DNA).
The first important man-made inorganic compound was ammonium nitratefor soil fertilization through the Haber process. Inorganic compounds are synthesized for use as catalystssuch as vanadium(V) oxideand titanium(III) chloride, or as reagentsin organic chemistrysuch as lithium aluminium hydride.
Subdivisions of inorganic chemistry are organometallic chemistry, cluster chemistryand bioinorganic chemistry. These fields are active areas of research in inorganic chemistry, aimed toward new catalysts, superconductors, and therapies.
Optics
Opticsis the branch of physicswhich involves the behaviour and properties of light, including its interactions with matterand the construction of instrumentsthat use or detectit. [ 1 ]Optics usually describes the behaviour of visible, ultraviolet, and infraredlight. Because light is an electromagnetic wave, other forms of electromagnetic radiationsuch as X-rays, microwaves, and radio wavesexhibit similar properties. [ 1 ]
Most optical phenomena can be accounted for using the classical electromagneticdescription of light. Complete electromagnetic descriptions of light are, however, often difficult to apply in practice. Practical optics is usually done using simplified models. The most common of these, geometric optics, treats light as a collection of raysthat travel in straight lines and bend when they pass through or reflect from surfaces. Physical opticsis a more comprehensive model of light, which includes waveeffects such as diffractionand interferencethat cannot be accounted for in geometric optics. Historically, the ray-based model of light was developed first, followed by the wave model of light. Progress in electromagnetic theory in the 19th century led to the discovery that light waves were in fact electromagnetic radiation.
Some phenomena depend on the fact that light has both wave-like and particle-like properties. Explanation of these effects requires quantum mechanics. When considering light's particle-like properties, the light is modelled as a collection of particles called " photons". Quantum opticsdeals with the application of quantum mechanics to optical systems.
Optical science is relevant to and studied in many related disciplines including astronomy, various engineeringfields, photography, and medicine(particularly ophthalmologyand optometry). Practical applications of optics are found in a variety of technologies and everyday objects, including mirrors, lenses, telescopes, microscopes, lasers, and fibre optics.
History
Main article: History of optics
See also: Timeline of electromagnetism and classical optics
The Nimrud lens
Optics began with the development of lenses by the ancient Egyptiansand Mesopotamians. The earliest known lenses, made from polished crystal, often quartz, date from as early as 700 BC for Assyrianlenses such as the Layard/ Nimrud lens. [ 2 ]The ancient RomansandGreeks filled glass ...philosophers, and the development of geometrical opticsin the Greco-Roman world. The wordopticscomes from the ancient Greekwordὀπτική, meaning "appearance, look". [ 3 ]
Greek philosophyon optics broke down into two opposing theories on how vision worked, the " intromission theory" and the "emission theory". [ 4 ]The intro-mission approach saw vision as coming from objects casting off copies of themselves (called eidola) that were captured by the eye. With many propagators including Democritus, Epicurus, Aristotleand their followers, this theory seems to have some contact with modern theories of what vision really is, but it remained only speculation lacking any experimental foundation.
Platofirst articulated the emission theory, the idea that visual perceptionis accomplished by rays emitted by the eyes.
http://ganeshscience.blogspot.com
papilliedema
Papilledema(orpapilloedema) is optic discswelling that is caused by increased intracranial pressure. The swelling is usually bilateral and can occur over a period of hours to weeks. Unilateral presentation is extremely rare. Papilledema is mostly seen as a symptom resulting from another pathophysiological process.
In intracranial hypertension, papilledema most commonly occurs bilaterally. When papilledema is found on fundoscopy, further evaluation is warranted as vision loss can result if the underlying condition is not treated. Further evaluation with a CT or MRI of the brain and/or spine is usually performed. Unilateral papilledema can suggest orbital pathology, such as an optic nerve glioma.
Signs and symptoms
Fundal photograph showing less severe papilledema
Papilledema may be asymptomatic or present with headache in the early stages. However it may progress to enlargement of the blind spot, blurring of vision, visual obscurations (inability to see in a particular part of the visual field for a period of time) and ultimately total loss of vision may occur.
The signs of papilledema that are seen using an ophthalmoscopeinclude:
*.venous engorgement (usually the first signs)
*.loss of venous pulsation
*.hemorrhages over and / or adjacent to the optic disc
*.blurring of optic margins
*.elevation of optic disc
*.Paton's lines = radial retinal lines cascading from the optic disc
On visual fieldexamination, the physician may elicit an enlarged blind spot; the visual acuity may remain relatively intact until papilledema is severe or prolonged.
Diagnosis
Checking the eyesfor signsof papilledema should be carried out whenever there is a clinical suspicion of raised intracranial pressure, and is recommended in newly onset headaches. This may be done by ophthalmoscopyor fundus photography, and possibly slit lampexamination.
Causes
Raised intracranial pressureas a result of one or more of the following:
*. Brain tumor, Pseudotumor Cerebri(also known as Idiopathic Intracranial Hypertension), Cerebral venous sinus thrombosisor Intracerebral hemorrhage
*. Respiratory failure [ 1 ]
*. Hypotonia
*. Isotretinoin, which is a powerful derivative of Vitamin A, rarely causes papilledema.
*. Hypervitaminosis A, in some people who take megadoses of nutritional supplements and vitamins.
*. Hyperammonemia, elevated level of ammonia in blood (including cerebral edema/intracranial pressure)
*. Guillain-Barré syndrome, due to elevated proteinlevels
*. Foster Kennedy syndrome(FKS)
*. Chiari Malformation
*. Tumorsof the frontal lobe
*. Acute Mountain Sicknessand High-altitude cerebral edema
*. Lyme disease(Lyme meningitisspecifically, when the bacterial infection is in the central nervous system, causing increased intracranial pressure).
*. Malignant Hypertension
*. Medulloblastoma
*.Orbital
*. Glaucoma: Central retinal vein occlusion, Cavernous sinus thrombosis
*.Local lesion: Optic neuritis, Ischemic optic neuropathy, Methanol poisoning, infiltration of the discby Glioma, Sarcoidosisand Lymphoma
*.Acute Lymphocytic leukemia(caused by infiltration of the retinal vessels by immature leukocytes)
*.Long periods of weightlessness( microgravity) for males
platinum
Platinumis a chemical elementwith the chemical symbolPtand an atomic numberof 78. It is a dense, malleable, ductile, highly unreactive, precious, gray-white transition metal. Its name is derived from the Spanish termplatina, which is literally translated into "little silver". [ 1 ] [ 2 ]
Platinum is a member of the platinum groupof elements and group 10of the periodic table of elements. It has six naturally occurring isotopes. It is one of the rarest elements in the Earth's crustwith an average abundance of approximately 5 μg/kg. It occurs in some nickeland copperores along with some nativedeposits, mostly in South Africa, which accounts for 80% of the world production. Because of its scarcity in the earth's crust, only a few hundred tonnesare produced annually, and is therefore highly valuable and is a major precious metal commodity.
Platinum is the least reactive metal. It has remarkable resistance to corrosion, even at high temperatures, and is therefore considered a noble metal. Consequently, platinum is often found chemically uncombined as native platinum. Because it occurs naturally in the alluvial sandsof various rivers, it was first used by pre-ColumbianSouth American natives to produce artifacts. It was referenced in European writings as early as 16th century, but it was not until Antonio de Ulloapublished a report on a new metal of Colombianorigin in 1748 that it became investigated by scientists.
Platinum is used in catalytic converters, laboratory equipment, electricalcontacts and electrodes, platinum resistance thermometers, dentistryequipment, and jewellery. Being a heavy metal, it leads to health issues upon exposure to its salts, but due to its corrosion resistance, it is not as toxic as some metals. [ 3 ]Compounds containing platinum, most notably cisplatin, are applied in chemotherapyagainst certain types of cancer. [ 4 ]
Characteristics
Physical
Pure platinum is a lustrous, ductile, and malleable, silver-white metal. [ 5 ]Platinum is more ductilethan gold, silver or copper, thus being the most ductile of pure metals, but it is less malleable than gold. [ 6 ] [ 7 ]Pure platinum is slightly harder than pure iron.[ citation needed]The metal has excellent resistance to corrosion, is stable at high temperatures and has stable electrical properties. It does not oxidize at any temperature, although it is corroded by halogens, cyanides, sulfur, and caustic alkalis. Platinum is insoluble in hydrochloricand nitric acid, but dissolves in hot aqua regiato form chloroplatinic acid, H2PtCl6.Blog Directory at OnToplist.comBlog Directory | Submit to Directories and Promote your BlogsBlog Directory at OnToplist.com
Diamond
In mineralogy,diamond(from the ancient Greekαδάμας –adámas"unbreakable") is a metastable allotrope of carbon, where the carbon atomsare arranged in a variation of the face-centered cubiccrystal structure called a diamond lattice. Diamond is less stablethan graphite, but the conversion rate from diamond to graphite is negligible at standard conditions. Diamond is renowned as a material with superlative physical qualities, most of which originate from the strong covalent bondingbetween its atoms. In particular, diamond has the highest hardnessand thermal conductivityof any bulk material. Those properties determine the major industrial application of diamond in cutting and polishing tools and the scientific applications in diamond knivesand diamond anvil cells.
Because of its extremely rigid lattice, it can be contaminated by very few types of impurities, such as boronand nitrogen. Small amounts of defects or impurities (about one per million of lattice atoms) color diamond blue (boron), yellow (nitrogen), brown ( lattice defects), green (radiation exposure), purple, pink, orange or red. Diamond also has relatively high optical dispersion(ability to disperse light of different colors).
Most natural diamonds are formed at high temperature and pressure at depths of 140 to 190 kilometers (87 to 118 mi) in the Earth's mantle. Carbon-containing minerals provide the carbon source, and the growth occurs over periods from 1 billion to 3.3 billion years (25% to 75% of the age of the Earth). Diamonds are brought close to the Earth's surface through deep volcanic eruptionsby a magma, which cools into igneous rocksknown as kimberlitesand lamproites. Diamonds can also be produced synthetically in a high-pressure high-temperatureprocess which approximately simulates the conditions in the Earth's mantle. An alternative, and completely different growth technique is chemical vapor deposition(CVD). Several non-diamond materials, which include cubic zirconiaand silicon carbideand are often called diamond simulants, resemble diamond in appearance and many properties. Special gemologicaltechniques have been developed to distinguish natural and synthetic diamondsand diamond simulants.Blog Directory at OnToplist.com
ELECTRO CONDUCTIVE THREAD
On a pound-per-pound basis, carbon nanotube-based fibers invented at Rice University have greater capacity to carry electrical current than copper cables of the same mass, according to new research. While individual nanotubes are capable of transmitting nearly 1,000 times more current than copper, the same tubes coalesced into a fiber using other technologies fail long before reaching that capacity.Credit: Illustration by Tanyia Johnson
[Click to enlarge image]
On a pound-per-pound basis, carbon nanotube-based fibers invented at Rice University have greater capacity to carry electrical current than copper cables of the same mass, according to new research.
While individual nanotubes are capable of transmitting nearly 1,000 times more current than copper, the same tubes coalesced into a fiber using other technologies fail long before reaching that capacity.
But a series of tests at Rice showed the wet-spun carbon nanotube fiber still handily beat copper, carrying up to four times as much current as a copper wire of the same mass.
Scanning electron microscope images show typical carbon nanotube fibers created at Rice University and broken into two by high-current-induced Joule heating. Rice researchers broke the fibers in different conditions -- air, argon, nitrogen and a vacuum -- to see how well they handled high current. The fibers proved overall to be better at carrying electrical current than copper cables of the same mass. (Credit: Kono Lab/Rice University)
That, said the researchers, makes nanotube-based cables an ideal platform for lightweight power transmission in systems where weight is a significant factor, like aerospace applications.
The analysis led by Rice professors Junichiro Kono and Matteo Pasquali appeared online this week in the journalAdvanced Functional Materials. Just a year ago the journal Science reported that Pasquali's lab, in collaboration with scientists at the Dutch firm Teijin Aramid, created a very strong conductive fiber out of carbon nanotubes.
Present-day transmission cables made of copper or aluminum are heavy because their low tensile strength requires steel-core reinforcement.
Scientists working with nanoscale materials have long thought there's a better way to move electricity from here to there. Certain types of carbon nanotubes can carry far more electricity than copper. The ideal cable would be made of long metallic "armchair" nanotubes that would transmit current over great distances with negligible loss, but such a cable is not feasible because it's not yet possible to manufacture pure armchairs in bulk, Pasquali said.
In the meantime, the Pasquali lab has created a method to spin fiber from a mix of nanotube types that still outperforms copper. The cable developed by Pasquali and Teijin Aramid is strong and flexible even though at 20 microns wide, it's thinner than a human hair.
Pasquali turned to Kono and his colleagues, including lead author Xuan Wang, a postdoctoral researcher at Rice, to quantify the fiber's capabilities.
Pasquali said there has been a disconnect between electrical engineers who study the current carrying capacity of conductors and materials scientists working on carbon nanotubes. "That has generated some confusion in the literature over the right comparisons to make," he said. "Jun and Xuan really got to the bottom of how to do these measurements well and compare apples to apples."
The researchers analyzed the fiber's "current carrying capacity" (CCC), or ampacity, with a custom rig that allowed them to test it alongside metal cables of the same diameter.
CONDUCTIVE TEXTILE
Aconductive textileis a fabricwhich can conduct electricity. Conductive textiles can be made with metal strands woveninto the construction of the textile. There is also an interest in semiconducting textiles, made by impregnating normal textiles with carbon- or metal-based powders. [ 1 ]
Conductive fibers consist of a non-conductive or less conductive substrate, which is then either coated or embedded with electrically conductive elements, often carbon, nickel, copper, gold, silver, or titanium. Substrates typically include cotton, polyester, nylon, and stainless steelto high performance fibers such as aramids and PBO. Straddling the worlds of textiles and wires, conductive fibers are sold either by weight or length, and measured in denieror AWG.
Because of the rapid growth in the kinds of conductive fibers and the uses of these fibers, a trade association has been formed to increase awareness, utilization, and possibly standarize terminology. The association is Conductive Fiber Manufacturers Council. [ 2 ]
Applications
Uses for conductive fibers and textiles may include staticdissipation, EMI shielding, [ 3 ]signal and power transfer in low resistanceversions, and as a heating elementin higher resistance versions. Their benefits over solid or stranded metal wires come from conductive fibers' flexibility and ability to use them in existing textile and wire machinery (weaving, knitting, braiding, etc.) Another more recent use is in the production of 'Stun gun' or Taser proof clothing, where the conductive textile is used as a sort of Faraday shield in a layer of the garment in question. Conductive fabric can also be used to make electrodesfor EEGand other medical applications; [ 4 ]such electrodes were used in a commercially-available sleep-monitoring device made by former company Zeo, Inc.Highly conductive stainless steel fiber is available.
CNT CARBON NANOTUBE
Carbon nanotubes(CNTs) are allotropes of carbonwith a cylindrical nanostructure. Nanotubes have been constructed with length-to-diameter ratio of up to 132,000,000:1, [ 1 ]significantly larger than for any other material. These cylindrical carbon moleculeshave unusual properties, which are valuable for nanotechnology, electronics, opticsand other fields of materials scienceand technology. In particular, owing to their extraordinary thermal conductivityand mechanical and electricalproperties, carbon nanotubes find applications as additives to various structural materials. For instance, nanotubes form a tiny portion of the material(s) in some (primarily carbon fiber) baseball bats, golf clubs, or car parts. [ 2 ]
Nanotubes are members of the fullerenestructural family. Their name is derived from their long, hollow structure with the walls formed by one-atom-thick sheets of carbon, called graphene. These sheets are rolled at specific and discrete (" chiral") angles, and the combination of the rolling angle and radius decides the nanotube properties; for example, whether the individual nanotube shell is a metalor semiconductor. Nanotubes are categorized as single-walled nanotubes(SWNTs) and multi-walled nanotubes(MWNTs). Individual nanotubes naturally align themselves into "ropes" held together by van der Waals forces, more specifically, pi-stacking.
Applied quantum chemistry, specifically, orbital hybridizationbest describes chemical bonding in nanotubes. The chemical bondingof nanotubes is composed entirely of sp 2 bonds, similar to those of graphite. These bonds, which are stronger than the sp 3 bondsfound in alkanesand diamond, provide nanotubes with their unique strength.
Types of carbon nanotubes and related structures
Terminology
There is no consensus on some terms describing carbon nanotubes in scientific literature: both "-wall" and "-walled" are being used in combination with "single", "double", "triple" or "multi", and the letter C is often omitted in the abbreviation; for example, multi-walled carbon nanotube (MWNT)
Most single-walled nanotubes (SWNT) have a diameter of close to 1 nanometer, with a tube length that can be many millions of times longer. The structure of a SWNT can be conceptualized by wrapping a one-atom-thick layer of graphite called graphene into a seamless cylinder. The way the graphene sheet is wrapped is represented by a pair of indices (n,m). The integersnandmdenote the number of unit vectorsalong two directions in the honeycomb crystal latticeof graphene. Ifm= 0, the nanotubes are called zigzag nanotubes, and ifn=m, the nanotubes are called armchair nanotubes. Otherwise, they are called chiral. The diameter of an ideal nanotube can be calculated from its (n,m) indices as follows
wherea= 0.246 nm.
SWNTs are an important variety of carbon nanotube because most of their properties change significantly with the (n,m) values, and this dependence is non-monotonic (see Kataura plot). In particular, their band gapcan vary from zero to about 2 eV and their electrical conductivity can show metallic or semiconducting behavior. Single-walled nanotubes are likely candidates for miniaturizing electronics. The most basic building block of these systems is the electric wire, and SWNTs with diameters of an order of a nanometer can be excellent conductors. [ 3 ] [ 4 ]One useful application of SWNTs is in the development of the first intermolecular field-effect transistors(FET). The first intermolecular logic gateusing SWCNT FETs was made in 2001. [ 5 ]A logic gate requires both a p-FET and an n-FET.
Subscribe to:
Posts (Atom)