Bioaccumulation is the gradual build up over time of a chemical in a living organism. This occurs either because the chemical is taken up faster than it can be used, or because the chemical cannot be broken down for use by the organism (that is, the chemical cannot be metabolized).
Bioaccumulation need not be a concern if the accumulated compound is not harmful. Compounds that are harmful to health, such as mercury, however, can accumulate in living tissues.
Chemical pollutants that are bioaccumulated come from many sources. Pesticides are an example of a contaminant that bioaccumulates in organisms. Rain can wash freshly sprayed pesticides into creeks, where they will eventually make their way to rivers, estuaries, and the ocean. Anther major source of toxic contaminants is the presence of compounds from industrial smokestacks and automobile emissions that return to the ground in rainfall. Deliberate discharge of compounds into water is another source of chemical pollutants.
Once a toxic pollutant is in the water or soil, it can easily enter the food chain. For example, in the water, pollutants adsorb or stick to small particles, including a tiny living organism called phytoplankton. Because there is so little pollutant stuck to each phytoplankton, the pollutant does not cause much damage at this level of the food web. However, a small animal such as a zooplankton might then consume the particle. One zooplankton that has eaten ten phytoplanktons would have ten times the pollutant level as the phytoplankton. As the zooplankton may be slow to metabolize or excrete the pollutant, the pollutant may build up or bioaccumulate within the organism. A small fish might then eat ten zooplankton. The fish would have 100 times the level of toxic pollutant as the phytoplankton. This multiplication would continue throughout the food web until high levels of contaminants have biomagnified in the top predator. While the amount of pollutant might have been small enough not to cause any damage in the lowest levels of the food web, the biomagnified amount might cause serious damage to organisms higher in the food web. This phenomenon is known as biomagnification.
Mercury contamination is a good example of the bioaccumulation process. Typically, mercury (or a chemical version called methylmercury) is taken up by bacteria and phytoplankton. Small fish eat the bacteria and phytoplankton and accumulate the mercury. The small fish are in turn eaten by larger fish, which can become food for humans and animals. The result can be the build up (biomagnification) of large concentrations of mercury in human and animal tissue.
One of the classic examples of bioaccumulation that resulted in biomagnification occurred with an insecticide called dichlorodiphenyltrichloroethane (DDT). DDT is an insecticide that was sprayed in the United States prior to 1972 to help control mosquitoes and other insects. Rain washed the DDT into creeks, where it eventually found its way into lakes and the ocean. The toxic pollutant bioaccumulated within each organism and then biomagnified through the food web to very high levels in predatory birds such as bald eagles, osprey, peregrine falcons and brown pelicans that ate the fish. Levels of DDT were high enough that the birds' eggshells became abnormally thin. As a result, the adult birds broke the shells of their unhatched offspring and the baby birds died. The population of these birds plummeted. DDT was finally banned in the United States in 1972, and since that time there have been dramatic increases in the populations of many predatory birds.
The bioaccumulation and biomagnification of toxic contaminants also can put human health at risk. When humans eat organisms that are relatively high in the food web, we can get high doses of some harmful chemicals. For example, marine fish such as swordfish, shark, and tuna often have bioaccumulated levels of mercury, and bluefish and striped bass sometimes have high concentrations of polychlorinated biphenyls (PCBs). The federal government and some states have issued advisories against eating too much of certain types of fish because of bioaccumulated and biomagnified levels of toxic pollutants.
Advances are being made in efforts to lessen the bioaccumulation of toxic compounds. Legislation banning the disposal of certain compounds in water helps to reduce the level of toxic compounds in the environment that are capable of being accumulated in the food chain. As well, microorganisms are being genetically engineered so as to be capable of using a toxic material such as mercury as a food source. Such bacteria can directly remove the compound from the environment.
Labels: BIOSCIENCE
Labels: BIOSCIENCE
Bioethanol is an alcohol made by fermenting the sugar components of plant materials and it is made mostly from sugar and starch crops. With advanced technology being developed, cellulosic biomass, such as trees and grasses, are also used as feedstocks for ethanol production. Ethanol can be used as a fuel for vehicles in its pure form, but it is usually used as a gasoline additive to increase octane and improve vehicle emissions. Bioethanol is widely used in the USA and in Brazil.
Biodiesel is made from vegetable oils, animal fats or recycled greases. Biodiesel can be used as a fuel for vehicles in its pure form, but it is usually used as a diesel additive to reduce levels of particulates, carbon monoxide, and hydrocarbons from diesel-powered vehicles. Biodiesel is produced from oils or fats using transesterification and is the most common biofuel in Europe.
Biofuels provided 1.8% of the world's transport fuel in 2008. Investment into biofuels production capacity exceeded $4 billion worldwide in 2007 and is growing.
Solid biofuels
Examples include wood, sawdust, grass cuttings, domestic refuse, charcoal, agricultural waste, non-food energy crops (see picture), and dried manure.
Notwithstanding the above noted study, numerous studies have shown that biomass fuels have significantly less impact on the environment than fossil based fuels. Of note is the U.S. Department of Energy Laboratory, Operated by Midwest Research Institute Biomass Power and Conventional Fossil Systems with and without CO2 Sequestration – Comparing the Energy Balance, Greenhouse Gas Emissions and Economics Study. Power generation emits significant amounts of greenhouse gases (GHGs), mainly carbon dioxide (CO2). Sequestering CO2 from the power plant flue gas can significantly reduce the GHGs from the power plant itself, but this is not the total picture. CO2 capture and sequestration consumes additional energy, thus lowering the plant's fuel-to-electricity efficiency. To compensate for this, more fossil fuel must be procured and consumed to make up for lost capacity. Taking this into consideration, the global warming potential (GWP), which is a combination of CO2, methane (CH4), and nitrous oxide (N2O) emissions, and energy balance of the system need to be examined using a life cycle approach. This takes into account the upstream processes which remain constant after CO2 sequestration as well as the steps required for additional power generation. firing biomass instead of coal led to a 148% reduction in GWP.A derivative of solid biofuel is biochar, which is produced by biomass pyrolysis. Bio-char made from agricultural waste can substitute for wood charcoal. As wood stock becomes scarce this alternative is gaining ground. In eastern Democratic Republic of Congo, for example, biomass briquettes are being marketed as an alternative to charcoal in order to protect Virunga National Park from deforestation associated with charcoal production.
Labels: BIO-FUELS
One of the major problems in the preparation of fruit juices and wine is cloudiness due primarily to the presence of pectins. These consist primarily of a-1, 4-anhydrogalacturonic acid polymers, with varying degrees of methyl esterification. They are associated with other plant polymers and, after homogenization, with the cell debris. The cloudiness that they cause is difficult to remove except by enzymic hydrolysis. Such treatment also has the additional benefits of reducing the solution viscosity, increasing the volume of juice produce (e.g. the yield of juice from white grapes can be raised by 15%), subtle but generally beneficial changes in the flavour and, in the case of wine-making, shorter fermentation times. The enzymes used in brewing are needed for saccharification of starch (bacterial and fungal a-amylases), breakdown of barley a-1.4- and a-1,3-linked glucan (b-glucanase) and hydrolysis of protein (neutral protease) t increase the (later) fermentation rate, particularly in the production of high-gravity beer, where extra protein is added. Cellulases are also occasionally used, particularly where wheat is used as adjunct to help break down the barley is b-glucans
.Due to the extreme heat stability of the B. amyloliquefaciens a-amylase where this is used, the wort must be boiled for a much longer period (e.g. 30 minutes) to inactivate it prior to fermentation. Papain is used in the later post-fermentation stages of beer-making to prevent the occurrence of protein-and tannin- containing ‘chill-haze’ otherwise formed on cooling the beer.Recently, ‘light’ beers, of lower calorific content, have become more popular. These require a higher degree of saccharification at lower starch concentrations to reduce the alcohol and total solid content of the beer. This may be achieved by the use of glucoamylase and/or fungal a-amylase during the fermentation.
A new enzyme preparation of fungal pectin lyase (EC 4.2.2.10) was shown to be useful for the production of cranberry juice and clarification of apple juice in the food industry (Semenova et al., 2006). A comparative study showed that the preparation of pectin lyase is competitive with commercial pectinase products. The molecular weight of homogeneous pectin lyase was 38 kDa. Properties of the homogenous enzyme were studies. This enzyme was most efficient in removing highly esterified pectin.
The zygomycete microfungus R. microsporus var. microsporus produced a 1,3-1,4-beta-D-glucan 4-glucanhydrolase (EC 3.21.73) which was able to hydrolyse beta-D-glucan that contains both the 1,3-and 1,4-bonds (barley beta-glucans) (Celestino et al., 2006). Its molecular mass was 33.7 kDa. Maximum activity was detected at pH values in the range of 4-5, and temperatures in the range of 50-60ºC. The enzyme was able to reduce both the viscosity of the brewermash and the filtration time, indicating its potential value for the brewing industry
Landbo et al, (2006) examined the clarification and haze-diminishing effects of alternative clarification strategies on black current juice including centrifugation and addition of acidic protease and pectinolytic enzyme preparation and gallic acid.
Labels: ENZYME BIOTECHNOLOGY
Lactose is hydrolysed to its constituent monosaccharides, glucose and galactose, by lactase. Glucose itself can be removed from some foodstuff, for example, prior to drying where glucose would cause discoloration, by fungal glucose oxidase.
Enzyme
Uses
Bacterial glucose isomerase Glucose ----> Invert sugar (i.e., fructose formation)
Bacterial a-Amylase Fungal amyloglucosidase Starch -----> Glucose
Fungal a-Amylas Partial degradation of starch in supplementation of amylase-deficient flour for bread making
Microbial rennets k-casein -----> para-casein (in milk curdling for cheese manufacture)
Papain (from papaya melon) Several protease applications including meat tenderization and dehazing of beer
Cellulose Cellulose -----> Glucose
Fungal pectinase Pectin degradation(In fruits and vegetable processing)
Glucose isomerase (immobilized) Production of invert sugar and of high fructose syrups from glucose
Penicillin acylase (immobilized) Hydrolysis of penicillin-G to make 6-aminopenicillanic acid for production of new penicillins
Aminoacylase (immobilized) Resolution of DL-amino acids to produce L-amino acids for food supplementation
Labels: ENZYME BIOTECHNOLOGY
Certain proteases have been used in food processing for centuries and any record of the discovery of their activity has been lost in the midst of time. Rennet (mainly chymosin), obtained from the fourth stomach (abomasum) of unweaned calves has been used traditionally in the production of cheese. Similarly, papain from the leaves and unripe fruit of the pawpaw (Carica papaya) has been used to tenderize meats.
These ancient discoveries have led to the development of various food applications for a wide range of available proteases from many sources, usually microbial.Proteases may be used at various pH values, and they may be highly specific in their choice of cleavable peptide links or quite non-specific. Proteolysis generally increases the solubility of proteins at their isoelectric points.The action of rennet in cheese making is an example of the hydrolysis of a specific peptide linkage, between phenylalanine and methionine residues (-Phe105Met106-) in the k-casein protein present in milk. Calf rennet, consisting of mainly chymosin with a small but variable proportion of pepsin, is a relatively expensive enzyme and various attempts have been made to find cheaper alternatives from microbial sources
These have ultimately proved to be successful and microbial rennets are used for about 70% of US cheese and 33% of cheese production worldwide. The development of unwanted bitterness in ripening cheese is an example of the role of proteases in flavour production in foodstuff. The action of endogenous proteases in meat after slaughter is complex but "hanging" meat allows flavour to develop, in addition to tenderizing it. It has been found that peptides with terminal acidic amino acid residues give meaty, appetizing flavours akin to that of monosodium glutamate.The presence of proteases during the ripening of cheese is not totally undesirable and a protease from Bacillus amyloliquefaciens may be used to promote flavour production in Cheddar cheese. Lipases from Mucor miehei or Aspergillus niger are sometimes used to give stronger flavours in Italian cheese by a modest lipolysis, increasing the amount of free butyric acid
Meat tenderization by the endogenous proteases in the muscle after slaughter is a complex process which varies with the nutritional, physiological and even psychological (i.e., frightened or not) state of the animal at the time of slaughter.Meat of older animals remains tough but can be tenderized by injecting inactive papain into the jugular vein of the live animals shortly before slaughter. Proteases are also used in the baking industry.
Labels: ENZYME BIOTECHNOLOGY
All enzymes contain a protein backbone. In some enzymes this is the only component in the structure. However there are additional non protein moieties usually present which may or may not participate in the catalytic activity of the enzyme.Covalently attached carbohydrate groups are commonly encountered structural features which often have no direct bearing on the catalytic activity, although they may well affect an enzyme's stability and solubility.Other factors often found are metal ions (cofactors) and low molecular weight organic molecules (coenzymes). These may be loosely or tightly bound by noncovalent or covalent forces. Enzymes are classified according to the report of a Nomenclature Committee appointed by the International Union of Biochemistry (1984).
Labels: ENZYME BIOTECHNOLOGY
For thousands of years processes such as brewing, bread-making and the production of cheese have involved the unrecognized use of enzymes. In the West the industrial understanding of enzymes revolved around yeast and malt, where traditional baking and brewing industries were rapidly expanding. Much of the early development of biochemistry was centred on yeast fermentations and processes for conversion of starch to sugar. Several enzymes, especially those used in starch processing, high-fructose syrup manufacture, textile desizing and detergent formulation, are now traded as commodity products in the world market. Relatively few enzymes, notably those in detergents, meat tenderizers and garden composting agents, are sold directly to the public.
Most are used by Industry to produce improved or novel products, to bypass long and involved chemical synthetic pathways or for use in the separation and purification of isomeric mixtures. Many of the most useful, but least-understood, uses of free enzymes are in the food industry.
There is now a raid proliferation of uses and potential uses for more highly purified enzyme preparation sin industrial processing, clinical medicine and laboratory practice. The range of pure enzymes now available commercially is rapidly increasing. Most of the enzymes used on an industrial scale are extracellular enzymes, i.e., enzymes that are normally excreted by the microorganisms to act upon their substrate in an external environment, and are analogous to the digestive enzymes of human beings and animals. Thus, when microorganisms produce enzymes to split large external molecules into an assimilable form, the enzymes are usually excreted into the fermentation media. In this way the fermentation broth form the cultivation of certain microorganisms, e.g. bacteria, yeasts or filamentous fungi, then becomes a major source of proteases, amylases and (to a lesser extent) cellulases, lipases, etc. Some intracellular enzymes are now being produced industrially and include glucose oxidase for food preservation, asparaginase for cancer therapy and penicillin acylase for antibiotic conversion. Since most cellular enzymes are by nature intracellular, more advances can be expected in this area.
Enzymes in soluble form have been used in the food industry for many years.This is especially so in the baking and brewing industries, the latter being the best example of traditional biotechnology.
Labels: ENZYME BIOTECHNOLOGY
Causes
Risk factors for pancreatic cancer include:
Age (particularly over 60)
Male sex (likeliness of up to 30% over females)
African-American ethnicity
Smoking. Cigarette smoking has a risk ratio of 1.74 with regard to pancreatic cancer; a decade of non-smoking after heavy smoking is associated with a risk ratio of 1.2.
Diets low in vegetables and fruits
Diets high in red meat
Diets high in sugar-sweetened drinks (soft drinks) risk ratio 1.87
Obesity
Diabetes mellitus is both risk factor for pancreatic cancer, and, as noted earlier, new onset diabetes can be an early sign of the disease.
Chronic pancreatitis has been linked, but is not known to be causal. The risk of pancreatic cancer in individuals with familial pancreatitis is particularly high.
Helicobacter pylori infection
Family history, 5–10% of pancreatic cancer patients have a family history of pancreatic cancer. The genes responsible for most of this clustering in families have yet to be identified. Pancreatic cancer has been associated with the following syndromes; autosomal recessive ataxia-telangiectasia and autosomal dominantly inherited mutations in the BRCA2 gene and PALB2 gene, Peutz-Jeghers syndrome due to mutations in the STK11 tumor suppressor gene, hereditary non-polyposis colon cancer (Lynch syndrome), familial adenomatous polyposis, and the familial atypical multiple mole melanoma-pancreatic cancer syndrome (FAMMM-PC) due to mutations in the CDKN2A tumor suppressor gene.
Gingivitis or periodontal disease
Ulcerative colitis
Australia and Canada being members of International Cancer Genome Consortium are leading efforts to map pancreatic cancer's complete genome.
Prevention
According to the American Cancer Society, there are no established guidelines for preventing pancreatic cancer, although cigarette smoking has been reported as responsible for 20–30% of pancreatic cancers.
The ACS recommends keeping a healthy weight, and increasing consumption of fruits, vegetables, and whole grains while decreasing red meat intake, although there is no consistent evidence that this will prevent or reduce pancreatic cancer specifically.In 2006 a large prospective cohort study of over 80,000 subjects failed to prove a definite association.The evidence in support of this lies mostly in small case-control studies.
In September 2006, a long-term study concluded that taking Vitamin D can substantially cut the risk of pancreatic cancer (as well as other cancers) by up to 50%, but this study needs to evaluate fully the risks, costs and potential benefits of taking Vitamin D.
Several studies, including one published on 1 June 2007, indicate that B vitamins such as B12, B6, and folate, can reduce the risk of pancreatic cancer when consumed in food, but not when ingested in vitamin tablet form.
Labels: CANCER
AUC, the area under the curve, represents the total drug exposure integrated over time and is an important parameter for both pharmacokinetic and pharmacodynamic analyses. As indicated in equation 1, the clearance is simply the ratio of the dose to the AUC, so that the higher the AUC for a given dose, the lower the clearance. If a drug is administered by continuous infusion and a steady state is achieved, the clearance can be estimated from a single measurement of the plasma drug concentration (Css) as in equation 2.
V is the volume of distribution, and K is the elimination constant. V is the volume of fluid in which the dose is initially diluted, and thus the higher the V, the lower the initial concentration. K is the elimination constant, which is inversely proportional to the half-life, the period of time that must elapse to reach a 50% decrease in plasma concentration. When the half-life is short, K is high and plasma concentrations decline rapidly. Thus both a high V and a high K result in relatively low plasma concentrations and a high clearance.
Labels: PHARMACEUTICALS
Biologically inspired nanotechnology
To put a nanometer-length scale into perspective, one nanometer—one billionth of a meter—is 100,000 times smaller than the width of a human hair. The building blocks in the biological world are nanometer-sized molecules such as proteins and sugars that, when assembled into intermediate length-scaled objects, deter- mine and control biological function.
In addition to developing nanoelectronics, many other features of the biosynthetic process lend themselves to devising nanotechnological materials. To do its work, nature uses highly sophisticated processes, for example, selection; self-organization; and self- assembly to provide an enormous range of "bio"-materials that ultimately form cells, tissues and organs. These materials exhibit remarkable powers of memory, replication, self-healing and self-repair.
In the case of bone, for example, nature has developed a composite ceramic material with overlap- ping levels of structural hierarchy and functional complexity. Self-assembled bio-organic materials, such as lipids and proteins, form nanoscale templates for inorganic components, guiding the final structure and shape of bone. It is the mixture of two very different materials—inorganic silicates and organic proteins— that gives bone its exceptional strength.
Biological membranes, which encapsulate all cellular machinery, represent another such example. Here, nanoscale organization and complex interactions of its constituents such as lipids and cholesterol, allow them to filter undesirable molecules from entering the cell. Recent advances in materials synthesis and biotechnology have enabled scientists to use these lessons from biology to produce highly ordered nanostructured materials with unique properties.
At Los Alamos National Laboratory, researchers recently have developed nanofilters by mimicking the biosynthesis of bone. These nanofilters are made up of ordinary glass, which has pores and channels that can be adjusted in size from four to 20 nanometers. By controlling the size and chemical properties of the pores, the constituents of complex mixtures can be separated. These nanofilters could be employed, for example, as masks to prevent exposure to biological pathogens such as viruses that can be as small as 30 nanometers in diameter. This work is supported by the Department of Energy's Office of Basic Energy Sciences in a joint project with Sandia National Laboratories and the University of New Mexico.
Los Alamos researchers also have developed miniaturized biosensors that can detect bioagents and markers for disease by mimicking cellular membranes and depositing these membranes onto optical chips. The surface of these membrane-based sensors look like the natural target of a biological agent, receptor molecules that decorate the surface of a cell membrane. By copying nature's functions using nanoscaled materials, the useful properties of sensors can be optimized permitting entirely new approaches to, for example, the early detection of disease. This cross-disciplinary effort spans fundamental science in Los Alamos' Strategic and Supporting Research Directorate and systems engineering in the Threat Reduction Directorate and is supported by the departments of Energy and Defense and by Laboratory-Directed Research and Development funds (see "Early Detection for Protection" for more on LDRD projects))
Labels: NANO SCIENCE
Nanotubes are members of the fullerene structural family, which also includes the spherical buckyballs. The ends of a nanotube might be capped with a hemisphere of the buckyball structure. Their name is derived from their size, since the diameter of a nanotube is on the order of a few nanometers (approximately 1/50,000th of the width of a human hair), while they can be up to 18 centimeters in length (as of 2010). Nanotubes are categorized as single-walled nanotubes (SWNTs) and multi-walled nanotubes (MWNTs).
The nature of the bonding of a nanotube is described by applied quantum chemistry, specifically, orbital hybridization. The chemical bonding of nanotubes is composed entirely of sp2 bonds, similar to those of graphite. This bonding structure, which is stronger than the sp3 bonds found in diamonds, provides the molecules with their unique strength. Nanotubes naturally align themselves into "ropes" held together by Van der Waals forces.
Extreme carbon nanotubes
Cycloparaphenylene
The observation of the longest carbon nanotubes (18.5 cm long) was reported in 2009. They were grown on Si substrates using an improved chemical vapor deposition (CVD) method and represent electrically uniform arrays of single-walled carbon nanotubes.
The shortest carbon nanotube is the organic compound cycloparaphenylene which was synthesized in the early 2009.
The thinnest carbon nanotube is armchair (2,2) CNT with a diameter of 3 Å. This nanotube was grown inside a multi-walled carbon nanotube. Assigning of carbon nanotube type was done by combination of high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy and density functional theory (DFT) calculations.
The thinnest freestanding single-walled carbon nanotube is about 4.3 Å in diameter. Researchers suggested that it can be either (5,1) or (4,2) SWCNT, but exact type of carbon nanotube remains questionable. (3,3), (4,3) and (5,1) carbon nanotubes (all about 4 Å in diameter) were unambiguously identified using more precise aberration-corrected high-resolution transmission electron microscopy. However, they were found inside of double-walled carbon nanotubes.
Labels: NANO SCIENCE
Symptoms of hepatocellular carcinoma
Abdominal mass
Abdominal pain
Emesis
Anemia
Back pain
Jaundice
Itching
Weight loss
Fever
Labels: CANCER
Another definition is a robot that allows precision interactions with nanoscale objects, or can manipulate with nanoscale resolution. Following this definition even a large apparatus such as an atomic force microscope can be considered a nanorobotic instrument when configured to perform nanomanipulation. Also, macroscale robots or microrobots that can move with nanoscale precision can also be considered nanorobots.
Nanomachines are largely in the research-and-development phase, but some primitive molecular machines have been tested. An example is a sensor having a switch approximately 1.5 nanometers across, capable of counting specific molecules in a chemical sample. The first useful applications of nanomachines, if such are ever built, might be in medical technology, where they might be used to identify cancer cells and destroy them. Another potential application is the detection of toxic chemicals, and the measurement of their concentrations, in the environment. Recently, Rice University has demonstrated a single-molecule car developed by a chemical process and includes buckyballs for wheels. It is actuated by controlling the environmental temperature and by positioning a scanning tunneling microscope tip.
Nanorobotics theory
Since nanorobots would be microscopic in size, it would probably be necessary for very large numbers of them to work together to perform microscopic and macroscopic tasks. These nanorobot swarms, both those incapable of replication (as in utility fog) and those capable of unconstrained replication in the natural environment (as in grey goo and its less common variants), are found in many science fiction stories, such as the Borg nanoprobes in Star Trek. The word "nanobot" (also "nanite", "nanogene", or "nanoant") is often used to indicate this fictional context and is an informal or even pejorative term to refer to the engineering concept of nanorobots. The word nanorobot is the correct technical term in the nonfictional context of serious engineering studies.
Some proponents of nanorobotics, in reaction to the grey goo scare scenarios that they earlier helped to propagate, hold the view that nanorobots capable of replication outside of a restricted factory environment do not form a necessary part of a purported productive nanotechnology, and that the process of self-replication, if it were ever to be developed, could be made inherently safe. They further assert that free-foraging replicators are in fact absent from their current plans for developing and using molecular manufacturing
Potential applications
Nanomedicine
Potential applications for nanorobotics in medicine include early diagnosis and targeted drug delivery for cancer, biomedical instrumentation, surgery, pharmacokinetics, monitoring of diabetes, and health care.
In such plans, future medical nanotechnology is expected to employ nanorobots injected into the patient to perform treatment on a cellular level. Such nanorobots intended for use in medicine should be non-replicating, as replication would needlessly increase device complexity, reduce reliability, and interfere with the medical mission. Instead, medical nanorobots are posited to be manufactured in hypothetical, carefully controlled nanofactories in which nanoscale machines would be solidly integrated into a supposed desktop-scale machine that would build macroscopic products.
The most detailed theoretical discussion of nanorobotics, including specific design issues such as sensing, power communication, navigation, manipulation, locomotion, and onboard computation, has been presented in the medical context of nanomedicine by Robert Freitas. Some of these discussions remain at the level of unbuildable generality and do not approach the level of detailed engineering.
Nanorobots
Nanotechnology promises futuristic applications such as microscopic robots that assemble other machines or travel inside the body to deliver drugs or do microsurgery.These machines will face some unique physics. At small scales, fluids appear as viscous as molasses, and Brownian motion makes everything incessantly shake. Taking inspiration from the biological motors of living cells, chemists are learning how to utilize protein dynamics to power microsize and nanosize machines with catalytic reactions.
Labels: NANO SCIENCE
A quantum dot is a semiconductor whose excitons are confined in all three spatial dimensions. As a result, they have properties that are between those of bulk semiconductors and those of discrete molecules. They were discovered by Louis E. Brus, who was then at Bell Labs. The term "Quantum Dot" was coined by Mark Reed. Researchers have studied quantum dots in transistors, solar cells, LEDs, and diode lasers. They have also investigated quantum dots as agents for medical imaging and hope to use them as qubits.
In layman's terms, quantum dots are semiconductors whose conducting characteristics are closely related to the size and shape of the individual crystal. Generally, the smaller the size of the crystal, the larger the band gap, the greater the difference in energy between the highest valence band and the lowest conduction band becomes, therefore more energy is needed to excite the dot, and concurrently, more energy is released when the crystal returns to its resting state. For example, in fluorescent dye applications, this equates to higher frequencies of light emitted after excitation of the dot as the crystal size grows smaller, resulting in a color shift from red to blue in the light emitted. The main advantages in using quantum dots is that because of the high level of control possible over the size of the crystals produced, it is possible to have very precise control over the conductive properties of the material.
Quantum dots are particularly significant for optical applications due to their high extinction co-efficient [13]. In electronic applications they have been proven to operate like a single-electron transistor and show the Coulomb blockade effect. Quantum dots have also been suggested as implementations of qubits for quantum information processing.
The ability to tune the size of quantum dots is advantageous for many applications. For instance, larger quantum dots have a greater spectrum-shift towards red compared to smaller dots, and exhibit less pronounced quantum properties. Conversely, the smaller particles allow one to take advantage of more subtle quantum effects.
Application
Researchers at Los Alamos National Laboratory have developed a wireless device that efficiently produces visible light, through energy transfer from thin layers of quantum wells to crystals above the layers.
Being zero dimensional, quantum dots have a sharper density of states than higher-dimensional structures. As a result, they have superior transport and optical properties, and are being researched for use in diode lasers, amplifiers, and biological sensors. Quantum dots may be excited within the locally enhanced electromagnetic field produced by the gold nanoparticles, which can then be observed from the surface Plasmon resonance in the photoluminescent excitation spectrum of (CdSe)ZnS nanocrystals. High-quality quantum dots are well suited for optical encoding and multiplexing applications due to their broad excitation profiles and narrow/symmetric emission spectra. The new generations of quantum dots have far-reaching potential for the study of intracellular processes at the single-molecule level, high-resolution cellular imaging, long-term in vivo observation of cell trafficking, tumor targeting, and diagnostics.
Labels: NANO SCIENCE
Nanotechnology shortened to "nanotech", is the study of the controlling of matter on an atomic and molecular scale. Generally nanotechnology deals with structures of the size 100 nanometers or smaller in at least one dimension, and involves developing materials or devices within that size. Nanotechnology is very diverse, ranging from extensions of conventional device physics to completely new approaches based upon molecular self-assembly, from developing new materials with dimensions on the nanoscale to investigating whether we can directly control matter on the atomic scale.
There has been much debate on the future implications of nanotechnology. Nanotechnology has the potential to create many new materials and devices with a vast range of applications, such as in medicine, electronics and energy production. On the other hand, nanotechnology raises many of the same issues as with any introduction of new technology, including concerns about the toxicity and environmental impact of nanomaterials, and their potential effects on global economics, as well as speculation about various doomsday scenarios. These concerns have led to a debate among advocacy groups and governments on whether special regulation of nanotechnology is warranted.
Current Research
1 Nanomaterials
2 Bottom-up approaches
3 Top-down approaches
4 Functional approaches
1 Nanomaterials
This includes subfields which develop or study materials having unique properties arising from their nanoscale dimensions. Interface and colloid science has given rise to many materials which may be useful in nanotechnology, such as carbon nanotubes and other fullerenes, and various nanoparticles and nanorods. Nanomaterials with fast ion transport are related also to nanoionics and nanoelectronics.
Nanoscale materials can also be used for bulk applications; most present commercial applications of nanotechnology are of this flavor.
Progress has been made in using these materials for medical applications; see Nanomedicine. Nanoscale materials are sometimes used in solar cells which combats the cost of traditional Silicon solar cells. Development of applications incorporating semiconductor nanoparticles to be used in the next generation of products, such as display technology, lighting, solar cells and biological imaging; see quantum dots.
2 Bottom-up approaches
These seek to arrange smaller components into more complex assemblies.
DNA nanotechnology utilizes the specificity of Watson–Crick basepairing to construct well-defined structures out of DNA and other nucleic acids.
Approaches from the field of "classical" chemical synthesis also aim at designing molecules with well-defined shape(e.g. bis peptide) . More generally, molecular self-assembly seeks to use concepts of supramolecular chemistry, and molecular recognition in particular, to cause single-molecule components to automatically arrange themselves into some useful conformation.
3 Top-down approaches
These seek to create smaller devices by using larger ones to direct their assembly.
Many technologies that descended from conventional solid-state silicon methods for fabricating microprocessors are now capable of creating features smaller than 100 nm, falling under the definition of nanotechnology. Giant magnetoresistance-based hard drives already on the market fit this description, as do atomic layer deposition (ALD) techniques. Peter Grünberg and Albert Fert received the Nobel Prize in Physics for their discovery of Giant magnetoresistance and contributions to the field of spintronics in 2007.
Solid-state techniques can also be used to create devices known as nanoelectromechanical systems or NEMS, which are related to microelectromechanical systems or MEMS.
Atomic force microscope tips can be used as a nanoscale "write head" to deposit a chemical upon a surface in a desired pattern in a process called dip pen nanolithography. This fits into the larger subfield of nanolithography.
Focused ion beams can directly remove material, or even deposit material when suitable pre-cursor gasses are applied at the same time. For example, this technique is used routinely to create sub-100 nm sections of material for analysis in Transmission electron microscopy.
4 Functional approaches
These seek to develop components of a desired functionality without regard to how they might be assembled.
Molecular electronics seeks to develop molecules with useful electronic properties. These could then be used as single-molecule components in a nanoelectronic device. For an example see rotaxane.
Synthetic chemical methods can also be used to create synthetic molecular motors, such as in a so-called nanocar.
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Leukemia (American English) or leukaemia (British and Canadian English; Greek leukos λευκός, "white"; aima αίμα, "blood") is a cancer of the blood or bone marrow characterized by an abnormal increase of blood cells, usually leukocytes (white blood cells). Leukemia is a broad term covering a spectrum of diseases. In turn, it is part of the even broader group of diseases called hematological neoplasms.Signs and symptoms
Damage to the bone marrow, by way of displacing the normal bone marrow cells with higher numbers of immature white blood cells, results in a lack of blood platelets, which are important in the blood clotting process. This means people with leukemia may easily become bruised, bleed excessively, or develop pinprick bleeds (petechiae).
White blood cells, which are involved in fighting pathogens, may be suppressed or dysfunctional. This could cause the patient's immune system to be unable to fight off a simple infection or to start attacking other body cells. Because leukemia prevents the immune system from working normally, some patients experience frequent infection, ranging from infected tonsils, sores in the mouth, or diarrhea to life-threatening pneumonia or opportunistic infections.
Finally, the red blood cell deficiency leads to anemia, which may cause dyspnea and pallor.
Some patients experience other symptoms. These symptoms might include feeling sick, such as having fevers, chills, night sweats and other flu-like symptoms, or feeling fatigued. Some patients experience nausea or a feeling of fullness due to an enlarged liver and spleen; this can result in unintentional weight loss. If the leukemic cells invade the central nervous system, then neurological symptoms (notably headaches) can occur.
All symptoms associated with leukemia can be attributed to other diseases. Consequently, leukemia is always diagnosed through medical tests.
The word leukemia, which means 'white blood', is derived from the disease's namesake high white blood cell counts that most leukemia patients have before treatment. The high number of white blood cells are apparent when a blood sample is viewed under a microscope. Frequently, these extra white blood cells are immature or dysfunctional. The excessive number of cells can also interfere with the level of other cells, causing a harmful imbalance in the blood count.
Some leukemia patients do not have high white blood cell counts visible during a regular blood count. This less-common condition is called aleukemia. The bone marrow still contains cancerous white blood cells which disrupt the normal production of blood cells. However, the leukemic cells are staying in the marrow instead of entering the bloodstream, where they would be visible in a blood test. For an aleukemic patient, the white blood cell counts in the bloodstream can be normal or low. Aleukemia can occur in any of the four major types of leukemia, and is particularly common in hairy cell leukemia.
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Breast cancer refers to cancers originating from breast tissue, most commonly from the inner lining of milk ducts or the lobules that supply the ducts with milk. Cancers originating from ducts are known as ductal carcinomas; those originating from lobules are known as lobular carcinomas. There are many different types of breast cancer, with different stages (spread), aggressiveness, and genetic makeup; survival varies greatly depending on those factors. Computerized models are available to predict survival.With best treatment and dependent on staging, 10-year disease-free survival varies from 98% to 10%. Treatment includes surgery, drugs (hormonal therapy and chemotherapy), and radiation.
Worldwide, breast cancer comprises 10.4% of all cancer incidence among women, making it the second most common type of non-skin cancer (after lung cancer) and the fifth most common cause of cancer death. In 2004, breast cancer caused 519,000 deaths worldwide (7% of cancer deaths; almost 1% of all deaths) Breast cancer is about 100 times more common in women than in men, although males tend to have poorer outcomes due to delays in diagnosis.
Some breast cancers require the hormones estrogen and progesterone to grow, and have receptors for those hormones. After surgery those cancers are treated with drugs that interfere with those hormones, usually tamoxifen, and with drugs that shut off the production of estrogen in the ovaries or elsewhere; this may damage the ovaries and end fertility. After surgery, low-risk, hormone-sensitive breast cancers may be treated with hormone therapy and radiation alone. Breast cancers without hormone receptors, or which have spread to the lymph nodes in the armpits, or which express certain genetic characteristics, are higher-risk, and are treated more aggressively. One standard regimen, popular in the U.S., is cyclophosphamide plus doxorubicin (Adriamycin), known as CA; these drugs damage DNA in the cancer, but also in fast-growing normal cells where they cause serious side effects. Sometimes a taxane drug, such as docetaxel, is added, and the regime is then known as CAT; taxane attacks the microtubules in cancer cells. An equivalent treatment, popular in Europe, is cyclophosphamide, methotrexate, and fluorouracil (CMF) . Monoclonal antibodies, such as trastuzumab (Herceptin), are used for cancer cells that have the HER2 mutation. Radiation is usually added to the surgical bed to control cancer cells that were missed by the surgery, which usually extends survival, although radiation exposure to the heart may cause damage and heart failure in the following years.
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Prostate cancer is a form of cancer that develops in the prostate, a gland in the male reproductive system. The cancer cells may metastasize (spread) from the prostate to other parts of the body, particularly the bones and lymph nodes. Prostate cancer may cause pain, difficulty in urinating, problems during sexual intercourse, or erectile dysfunction. Other symptoms can potentially develop during later stages of the disease.
Rates of detection of prostate cancers vary widely across the world, with South and East Asia detecting less frequently than in Europe, and especially the United States. Prostate cancer tends to develop in men over the age of fifty and although it is one of the most prevalent types of cancer in men, many never have symptoms, undergo no therapy, and eventually die of other causes. This is because cancer of the prostate is, in most cases, slow-growing, symptom-free, and since men with the condition are older they often die of causes unrelated to the prostate cancer, such as heart/circulatory disease, pneumonia, other unconnected cancers, or old age. Many factors, including genetics and diet, have been implicated in the development of prostate cancer. The presence of prostate cancer may be indicated by symptoms, physical examination, prostate specific antigen (PSA), or biopsy. There is controversy about the accuracy of the PSA test and the value of screening. Suspected prostate cancer is typically confirmed by taking a biopsy of the prostate and examining it under a microscope. Further tests, such as CT scans and bone scans, may be performed to determine whether prostate cancer has spread.
Treatment options for prostate cancer with intent to cure are primarily surgery, radiation therapy, and proton therapy. Other treatments, such as hormonal therapy, chemotherapy, cryosurgery, and high intensity focused ultrasound (HIFU) also exist, depending on the clinical scenario and desired outcome.
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Labels: CANCER