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124-626: Indole is a solid at room temperature. It occurs naturally in human feces and has an intense fecal odor . At very low concentrations, however, it has a flowery smell, and is a constituent of many perfumes . It also occurs in coal tar . It has been identified in cannabis . It is the main volatile compound in stinky tofu . When indole is a substituent on a larger molecule, it is called an indolyl group by systematic nomenclature . Indole undergoes electrophilic substitution , mainly at position 3 (see diagram in right margin). Substituted indoles are structural elements of (and for some compounds,

248-511: A rock sample is a random aggregate of minerals and/or mineraloids , and has no specific chemical composition. The vast majority of the rocks of the Earth's crust consist of quartz (crystalline SiO 2 ), feldspar, mica, chlorite , kaolin , calcite, epidote , olivine , augite , hornblende , magnetite , hematite , limonite and a few other minerals. Some minerals, like quartz , mica or feldspar are common, while others have been found in only

372-405: A significant source of antibiotic-resistant S. aureus , especially in times of outbreak. In a 2008 study by Boost, O'Donoghue, and James, it was found that just about 90% of S. aureus colonized within pet dogs presented as resistant to at least one antibiotic. The nasal region has been implicated as the most important site of transfer between dogs and humans. Staphylococcus aureus is one of

496-453: A virulence factor , primarily by being a bacterial antioxidant which helps the microbe evade the reactive oxygen species which the host immune system uses to kill pathogens. Mutant strains of S. aureus modified to lack staphyloxanthin are less likely to survive incubation with an oxidizing chemical, such as hydrogen peroxide , than pigmented strains. Mutant colonies are quickly killed when exposed to human neutrophils , while many of

620-418: A 1995 study by Hofman et al., these factors may include age, sex, diabetes , and smoking. They also determined some genetic variations in humans that lead to an increased ability for S. aureus to colonize, notably a polymorphism in the glucocorticoid receptor gene that results in larger corticosteroid production. In conclusion, there is evidence that any strain of this bacterium can become invasive, as this

744-525: A coin, are chemically identical throughout, many other common materials comprise a number of different substances packed together. For example, a typical rock is an aggregate of several different minerals and mineraloids , with no specific chemical composition. Wood is a natural organic material consisting primarily of cellulose fibers embedded in a matrix of organic lignin . In materials science, composites of more than one constituent material can be designed to have desired properties. The forces between

868-428: A common cause of skin infections including abscesses , respiratory infections such as sinusitis , and food poisoning . Pathogenic strains often promote infections by producing virulence factors such as potent protein toxins , and the expression of a cell-surface protein that binds and inactivates antibodies . S. aureus is one of the leading pathogens for deaths associated with antimicrobial resistance and

992-541: A composite made up of a thermoplastic matrix such as acrylonitrile butadiene styrene (ABS) in which calcium carbonate chalk, talc , glass fibers or carbon fibers have been added for strength, bulk, or electro-static dispersion. These additions may be referred to as reinforcing fibers, or dispersants, depending on their purpose. Thus, the matrix material surrounds and supports the reinforcement materials by maintaining their relative positions. The reinforcements impart their special mechanical and physical properties to enhance

1116-1043: A few locations worldwide. The largest group of minerals by far is the silicates (most rocks are ≥95% silicates), which are composed largely of silicon and oxygen , with the addition of ions of aluminium, magnesium , iron, calcium and other metals. Ceramic solids are composed of inorganic compounds, usually oxides of chemical elements. They are chemically inert, and often are capable of withstanding chemical erosion that occurs in an acidic or caustic environment. Ceramics generally can withstand high temperatures ranging from 1,000 to 1,600 °C (1,830 to 2,910 °F). Exceptions include non-oxide inorganic materials, such as nitrides , borides and carbides . Traditional ceramic raw materials include clay minerals such as kaolinite , more recent materials include aluminium oxide ( alumina ). The modern ceramic materials, which are classified as advanced ceramics, include silicon carbide and tungsten carbide . Both are valued for their abrasion resistance, and hence find use in such applications as

1240-511: A force applied to the surface. Unlike a liquid, a solid object does not flow to take on the shape of its container, nor does it expand to fill the entire available volume like a gas. The atoms in a solid are bound to each other, either in a regular geometric lattice ( crystalline solids , which include metals and ordinary ice ), or irregularly (an amorphous solid such as common window glass). Solids cannot be compressed with little pressure whereas gases can be compressed with little pressure because

1364-437: A formula for indole. Certain indole derivatives were important dyestuffs until the end of the 19th century. In the 1930s, interest in indole intensified when it became known that the indole substituent is present in many important alkaloids , known as indole alkaloids (e.g., tryptophan and auxins ), and it remains an active area of research today. Indole is biosynthesized in the shikimate pathway via anthranilate . It

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1488-438: A host to be successful, S. aureus must survive such damages caused by the hosts' defenses. The two protein complex RexAB encoded by S. aureus is employed in the recombinational repair of DNA double-strand breaks. Many mRNAs in S. aureus carry three prime untranslated regions (3'UTR) longer than 100 nucleotides , which may potentially have a regulatory function. Further investigation of i caR mRNA (mRNA coding for

1612-405: A large range of infectious ability within the species. It has been proposed that one possible reason for the great deal of heterogeneity within the species could be due to its reliance on heterogeneous infections. This occurs when multiple different types of S. aureus cause an infection within a host. The different strains can secrete different enzymes or bring different antibiotic resistances to

1736-580: A material can absorb before mechanical failure, while fracture toughness (denoted K Ic ) describes the ability of a material with inherent microstructural flaws to resist fracture via crack growth and propagation. If a material has a large value of fracture toughness , the basic principles of fracture mechanics suggest that it will most likely undergo ductile fracture. Brittle fracture is very characteristic of most ceramic and glass-ceramic materials that typically exhibit low (and inconsistent) values of K Ic . For an example of applications of ceramics,

1860-558: A material that indicates its ability to conduct heat . Solids also have a specific heat capacity , which is the capacity of a material to store energy in the form of heat (or thermal lattice vibrations). Electrical properties include both electrical resistivity and conductivity , dielectric strength , electromagnetic permeability , and permittivity . Electrical conductors such as metals and alloys are contrasted with electrical insulators such as glasses and ceramics. Semiconductors behave somewhere in between. Whereas conductivity in metals

1984-440: A meltdown of the metallic parts. Work is also being done in developing ceramic parts for gas turbine engines . Turbine engines made with ceramics could operate more efficiently, giving aircraft greater range and payload for a set amount of fuel. Such engines are not in production, however, because the manufacturing of ceramic parts in the sufficient precision and durability is difficult and costly. Processing methods often result in

2108-468: A member of the Bacillota , and is a usual member of the microbiota of the body, frequently found in the upper respiratory tract and on the skin . It is often positive for catalase and nitrate reduction and is a facultative anaerobe , meaning that it can grow without oxygen. Although S. aureus usually acts as a commensal of the human microbiota, it can also become an opportunistic pathogen , being

2232-578: A metallic conductor, current is carried by the flow of electrons, but in semiconductors, current can be carried either by electrons or by the positively charged " holes " in the electronic band structure of the material. Common semiconductor materials include silicon, germanium and gallium arsenide . Many traditional solids exhibit different properties when they shrink to nanometer sizes. For example, nanoparticles of usually yellow gold and gray silicon are red in color; gold nanoparticles melt at much lower temperatures (~300 °C for 2.5 nm size) than

2356-422: A non-crystalline intergranular phase. Glass-ceramics are used to make cookware (originally known by the brand name CorningWare ) and stovetops that have high resistance to thermal shock and extremely low permeability to liquids. The negative coefficient of thermal expansion of the crystalline ceramic phase can be balanced with the positive coefficient of the glassy phase. At a certain point (~70% crystalline)

2480-529: A periodic lattice. Mathematically, the potential of the ion cores can be treated by various models, the simplest being the nearly free electron model . Minerals are naturally occurring solids formed through various geological processes under high pressures. To be classified as a true mineral, a substance must have a crystal structure with uniform physical properties throughout. Minerals range in composition from pure elements and simple salts to very complex silicates with thousands of known forms. In contrast,

2604-404: A person at particular risk of septic arthritis , staphylococcal endocarditis (infection of the heart valves), and pneumonia . Staphylococcus aureus is a significant cause of chronic biofilm infections on medical implants , and the repressor of toxins is part of the infection pathway. Staphylococcus aureus can lie dormant in the body for years undetected. Once symptoms begin to show,

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2728-438: A piezoelectric response several times larger than the traditional piezoelectric material quartz (crystalline SiO 2 ). The deformation (~0.1%) lends itself to useful technical applications such as high-voltage sources, loudspeakers, lasers, as well as chemical, biological, and acousto-optic sensors and/or transducers. Staphylococcus aureus Staphylococcus aureus is a gram-positive spherically shaped bacterium ,

2852-499: A resin during processing, which is then shaped into a final form. Polymers that have been around, and that are in current widespread use, include carbon-based polyethylene , polypropylene , polyvinyl chloride , polystyrene , nylons, polyesters , acrylics , polyurethane , and polycarbonates , and silicon-based silicones . Plastics are generally classified as "commodity", "specialty" and "engineering" plastics. Composite materials contain two or more macroscopic phases, one of which

2976-491: A role in intraspecies competition confers an advantage by promoting successful colonisation in polymicrobial communities such as the nasopharynx and lung by outcompeting lesser strains. There are also T7 effector proteins that play role a in pathogenesis, for example mutational studies of S. aureus have suggested that EsxB and EsxC contribute to persistent infection in a murine abscess model. EsxX has been implicated in neutrophil lysis, therefore suggested as contributing to

3100-447: A severe form of which can be seen in newborns . Antibiotics are commonly used to target overgrowth of S. aureus but their benefit is limited and they increase the risk of antimicrobial resistance . For these reasons, they are only recommended for people who not only present symptoms on the skin but feel systematically unwell. Staphylococcus aureus is also responsible for food poisoning and achieves this by generating toxins in

3224-442: A significant portion of the fields of solid-state chemistry, physics, materials science and engineering. Metallic solids are held together by a high density of shared, delocalized electrons, known as " metallic bonding ". In a metal, atoms readily lose their outermost ("valence") electrons , forming positive ions . The free electrons are spread over the entire solid, which is held together firmly by electrostatic interactions between

3348-454: A single crystal, but instead are made of a large number of single crystals, known as crystallites , whose size can vary from a few nanometers to several meters. Such materials are called polycrystalline . Almost all common metals, and many ceramics , are polycrystalline. In other materials, there is no long-range order in the position of the atoms. These solids are known as amorphous solids ; examples include polystyrene and glass. Whether

3472-435: A solid is crystalline or amorphous depends on the material involved, and the conditions in which it was formed. Solids that are formed by slow cooling will tend to be crystalline, while solids that are frozen rapidly are more likely to be amorphous. Likewise, the specific crystal structure adopted by a crystalline solid depends on the material involved and on how it was formed. While many common objects, such as an ice cube or

3596-401: A surgical abscess during a procedure he was performing. He named it Staphylococcus after its clustered appearance evident under a microscope. Then, in 1884, German scientist Friedrich Julius Rosenbach identified Staphylococcus aureus , discriminating and separating it from Staphylococcus albus , a related bacterium. In the early 1930s, doctors began to use a more streamlined test to detect

3720-432: A variety of methods. The main industrial routes start from aniline via vapor-phase reaction with ethylene glycol in the presence of catalysts : In general, reactions are conducted between 200 and 500 °C. Yields can be as high as 60%. Other precursors to indole include formyltoluidine , 2-ethylaniline, and 2-(2-nitrophenyl)ethanol, all of which undergo cyclizations . The Leimgruber–Batcho indole synthesis

3844-692: A way that the strain is directly proportional to the stress ( Hooke's law ). The coefficient of the proportion is called the modulus of elasticity or Young's modulus . This region of deformation is known as the linearly elastic region. Three models can describe how a solid responds to an applied stress: Many materials become weaker at high temperatures. Materials that retain their strength at high temperatures, called refractory materials , are useful for many purposes. For example, glass-ceramics have become extremely useful for countertop cooking, as they exhibit excellent mechanical properties and can sustain repeated and quick temperature changes up to 1000 °C. In

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3968-471: A wide distribution of microscopic flaws that frequently play a detrimental role in the sintering process, resulting in the proliferation of cracks, and ultimate mechanical failure. Glass-ceramic materials share many properties with both non-crystalline glasses and crystalline ceramics . They are formed as a glass, and then partially crystallized by heat treatment, producing both amorphous and crystalline phases so that crystalline grains are embedded within

4092-411: A wide range of antibodies by immunoaffinity chromatography . Transpeptidases, such as the sortases responsible for anchoring factors like protein A to the staphylococcal peptidoglycan, are being studied in hopes of developing new antibiotics to target MRSA infections. Some strains of S. aureus are capable of producing staphyloxanthin — a golden-coloured carotenoid pigment . This pigment acts as

4216-414: A wide variety of polymers and plastics . Wood is a natural organic material consisting primarily of cellulose fibers embedded in a matrix of lignin . Regarding mechanical properties, the fibers are strong in tension, and the lignin matrix resists compression. Thus wood has been an important construction material since humans began building shelters and using boats. Wood to be used for construction work

4340-511: Is C3, which is 10 times more reactive than benzene . For example, it is alkylated by phosphorylated serine in the biosynthesis of the amino acid tryptophan. Vilsmeier–Haack formylation of indole will take place at room temperature exclusively at C3. Since the pyrrolic ring is the most reactive portion of indole, electrophilic substitution of the carbocyclic (benzene) ring generally takes place only after N1, C2, and C3 are substituted. A noteworthy exception occurs when electrophilic substitution

4464-443: Is DNA endonuclease toxin secreted by S. aureus , has been shown to inhibit growth of competitor S. aureus strain in vitro . EsaD is cosecreted with chaperone EsaE, which stabilises EsaD structure and brings EsaD to EssC for secretion. Strains that produce EsaD also co-produce EsaG, a cytoplasmic anti-toxin that protects the producer strain from EsaD's toxicity. TspA is another toxin that mediates intraspecies competition. It

4588-463: Is a bacteriostatic toxin that has a membrane depolarising activity facilitated by its C-terminal domain . Tsai is a transmembrane protein that confers immunity to the producer strain of TspA, as well as the attacked strains. There is genetic variability of the C-terminal domain of TspA therefore, it seems like the strains may produce different TspA variants to increase competitiveness. Toxins that play

4712-400: Is a great deal of genetic variation within the S. aureus species . A study by Fitzgerald et al. (2001) revealed that approximately 22% of the S. aureus genome is non-coding and thus can differ from bacterium to bacterium. An example of this difference is seen in the species' virulence. Only a few strains of S. aureus are associated with infections in humans. This demonstrates that there is

4836-445: Is a highly specialised multi-protein unit that is embedded in the cell envelope with the function of translocating effector proteins from inside of the cell to the extracellular space or into a target host cytosol. The exact structure and function of T7SS is yet to be fully elucidated. Currently, four proteins are known components of S. aureus type VII secretion system; EssC is a large integral membrane ATPase - which most likely powers

4960-686: Is also a fundamental feature of many biological materials and the manner by which the structures are assembled from the molecular level up. Thus, self-assembly is emerging as a new strategy in the chemical synthesis of high performance biomaterials. Physical properties of elements and compounds that provide conclusive evidence of chemical composition include odor, color, volume, density (mass per unit volume), melting point, boiling point, heat capacity, physical form and shape at room temperature (solid, liquid or gas; cubic, trigonal crystals, etc.), hardness, porosity, index of refraction and many others. This section discusses some physical properties of materials in

5084-413: Is an efficient method of synthesizing indole and substituted indoles. Originally disclosed in a patent in 1976, this method is high-yielding and can generate substituted indoles. This method is especially popular in the pharmaceutical industry , where many pharmaceutical drugs are made up of specifically substituted indoles. One of the oldest and most reliable methods for synthesizing substituted indoles

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5208-658: Is an intermediate in the biosynthesis of tryptophan , where it stays inside the tryptophan synthase molecule between the removal of 3-phospho-glyceraldehyde and the condensation with serine . When indole is needed in the cell, it is usually produced from tryptophan by tryptophanase . As an intercellular signal molecule , indole regulates various aspects of bacterial physiology, including spore formation, plasmid stability, resistance to drugs , biofilm formation, and virulence . A number of indole derivatives have important cellular functions, including neurotransmitters such as serotonin . Common classical methods applied for

5332-662: Is anchored to staphylococcal peptidoglycan pentaglycine bridges (chains of five glycine residues) by the transpeptidase sortase A. Protein A, an IgG -binding protein, binds to the Fc region of an antibody . In fact, studies involving mutation of genes coding for protein A resulted in a lowered virulence of S. aureus as measured by survival in blood, which has led to speculation that protein A-contributed virulence requires binding of antibody Fc regions. Protein A in various recombinant forms has been used for decades to bind and purify

5456-686: Is carried out in conditions sufficiently acidic to exhaustively protonate C3. In this case, C5 is the most common site of electrophilic attack. Gramine , a useful synthetic intermediate, is produced via a Mannich reaction of indole with dimethylamine and formaldehyde . It is the precursor to indole-3-acetic acid and synthetic tryptophan. The N–H center has a p K a of 21 in DMSO , so that very strong bases such as sodium hydride or n -butyl lithium and water-free conditions are required for complete deprotonation . The resulting organometalic derivatives can react in two ways. The more ionic salts such as

5580-469: Is caused by electrons, both electrons and holes contribute to current in semiconductors. Alternatively, ions support electric current in ionic conductors . Many materials also exhibit superconductivity at low temperatures; they include metallic elements such as tin and aluminium, various metallic alloys, some heavily doped semiconductors, and certain ceramics. The electrical resistivity of most electrical (metallic) conductors generally decreases gradually as

5704-416: Is commonly known as lumber or timber . In construction, wood is not only a structural material, but is also used to form the mould for concrete. Wood-based materials are also extensively used for packaging (e.g. cardboard) and paper, which are both created from the refined pulp. The chemical pulping processes use a combination of high temperature and alkaline (kraft) or acidic (sulfite) chemicals to break

5828-549: Is extremely prevalent in persons with atopic dermatitis (AD), more commonly known as eczema. It is mostly found in fertile, active places, including the armpits, hair, and scalp. Large pimples that appear in those areas may exacerbate the infection if lacerated. Colonization of S. aureus drives inflammation of AD. S. aureus is believed to exploit defects in the skin barrier of persons with atopic dermatitis, triggering cytokine expression and therefore exacerbating symptoms. This can lead to staphylococcal scalded skin syndrome ,

5952-407: Is generally associated with breaks in the skin or mucosal membranes due to surgery, injury, or use of intravascular devices such as cannulas , hemodialysis machines, or hypodermic needles . Once the bacteria have entered the bloodstream, they can infect various organs, causing infective endocarditis , septic arthritis , and osteomyelitis . This disease is particularly prevalent and severe in

6076-422: Is highly dependent upon human factors. Though S. aureus has quick reproductive and micro-evolutionary rates, there are multiple barriers that prevent evolution with the species. One such barrier is AGR, which is a global accessory gene regulator within the bacteria. This such regulator has been linked to the virulence level of the bacteria. Loss of function mutations within this gene have been found to increase

6200-426: Is nonmotile and does not form spores . In medical literature, the bacterium is often referred to as S. aureus , Staph aureus or Staph a. . S. aureus appears as staphylococci (grape-like clusters) when viewed through a microscope, and has large, round, golden-yellow colonies, often with hemolysis , when grown on blood agar plates . S. aureus reproduces asexually by binary fission . Complete separation of

6324-876: Is not effective in eradicating such infections. An alternative to postsurgical antibiotic treatment is using antibiotic-loaded, dissolvable calcium sulfate beads, which are implanted with the medical device. These beads can release high doses of antibiotics at the desired site to prevent the initial infection. Novel treatments for S. aureus biofilm involving nano silver particles, bacteriophages , and plant-derived antibiotic agents are being studied. These agents have shown inhibitory effects against S. aureus embedded in biofilms. A class of enzymes have been found to have biofilm matrix-degrading ability, thus may be used as biofilm dispersal agents in combination with antibiotics. Staphylococcus aureus can survive on dogs, cats, and horses, and can cause bumblefoot in chickens. Some believe health-care workers' dogs should be considered

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6448-460: Is often ceramic. For example, a continuous matrix, and a dispersed phase of ceramic particles or fibers. Applications of composite materials range from structural elements such as steel-reinforced concrete, to the thermally insulative tiles that play a key and integral role in NASA's Space Shuttle thermal protection system , which is used to protect the surface of the shuttle from the heat of re-entry into

6572-497: Is one of the most common causes of bacteremia and infective endocarditis . Additionally, it can cause various skin and soft-tissue infections, particularly when skin or mucosal barriers have been breached. Staphylococcus aureus infections can spread through contact with pus from an infected wound, skin-to-skin contact with an infected person, and contact with objects used by an infected person such as towels, sheets, clothing, or athletic equipment. Joint replacements put

6696-450: Is primarily protonated at the C3, rather than N1, owing to the enamine -like reactivity of the portion of the molecule located outside of the benzene ring. The protonated form has a p K a of −3.6. The sensitivity of many indolic compounds (e.g., tryptamines ) under acidic conditions is caused by this protonation. The most reactive position on indole for electrophilic aromatic substitution

6820-407: Is recommended to keep the food below 4.4 or above 60 °C (below 40 or above 140 °F). Staphylococcus aureus is a common cause of major bone and joint infections, including osteomyelitis , septic arthritis , and infections following joint replacement surgeries. Staphylococcus aureus is a leading cause of bloodstream infections throughout much of the industrialized world. Infection

6944-568: Is still one of the five most common causes of hospital-acquired infections and is often the cause of wound infections following surgery . Each year, around 500,000 hospital patients in the United States contract a staphylococcal infection , chiefly by S. aureus . Up to 50,000 deaths each year in the U.S. are linked to staphylococcal infection. In 1880, Alexander Ogston , a Scottish surgeon, discovered that Staphylococcus can cause wound infections after noticing groups of bacteria in pus from

7068-413: Is that the biofilm matrix protects the embedded cells by acting as a barrier to prevent antibiotic penetration. However, the biofilm matrix is composed with many water channels, so this hypothesis is becoming increasingly less likely, but a biofilm matrix possibly contains antibiotic‐degrading enzymes such as β-lactamases, which can prevent antibiotic penetration. Another hypothesis is that the conditions in

7192-500: Is the Fischer indole synthesis , developed in 1883 by Emil Fischer . Although the synthesis of indole itself is problematic using the Fischer indole synthesis, it is often used to generate indoles substituted in the 2- and/or 3-positions. Indole can still be synthesized, however, using the Fischer indole synthesis by reacting phenylhydrazine with pyruvic acid followed by decarboxylation of

7316-409: Is the ability of crystals to generate a voltage in response to an applied mechanical stress. The piezoelectric effect is reversible in that piezoelectric crystals, when subjected to an externally applied voltage, can change shape by a small amount. Polymer materials like rubber, wool, hair, wood fiber, and silk often behave as electrets . For example, the polymer polyvinylidene fluoride (PVDF) exhibits

7440-637: Is the main cause of Staphylococcus implant infections. Biofilms are groups of microorganisms, such as bacteria, that attach to each other and grow on wet surfaces. The S. aureus biofilm is embedded in a glycocalyx slime layer and can consist of teichoic acids , host proteins, extracellular DNA (eDNA) and sometimes polysaccharide intercellular antigen (PIA). S. aureus biofilms are important in disease pathogenesis, as they can contribute to antibiotic resistance and immune system evasion. S. aureus biofilm has high resistance to antibiotic treatments and host immune response. One hypothesis for explaining this

7564-400: Is the study of the behavior of solid matter under external actions such as external forces and temperature changes. A solid does not exhibit macroscopic flow, as fluids do. Any degree of departure from its original shape is called deformation . The proportion of deformation to original size is called strain. If the applied stress is sufficiently low, almost all solid materials behave in such

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7688-483: Is used in capacitors. A capacitor is an electrical device that can store energy in the electric field between a pair of closely spaced conductors (called 'plates'). When voltage is applied to the capacitor, electric charges of equal magnitude, but opposite polarity, build up on each plate. Capacitors are used in electrical circuits as energy-storage devices, as well as in electronic filters to differentiate between high-frequency and low-frequency signals. Piezoelectricity

7812-421: The betablocker pindolol . The name indole is a portmanteau of the words ind igo and ole um , since indole was first isolated by treatment of the indigo dye with oleum. Indole chemistry began to develop with the study of the dye indigo . Indigo can be converted to isatin and then to oxindole . Then, in 1866, Adolf von Baeyer reduced oxindole to indole using zinc dust. In 1869, he proposed

7936-492: The daughter cells is mediated by S. aureus autolysin , and in its absence or targeted inhibition, the daughter cells remain attached to one another and appear as clusters. Staphylococcus aureus is catalase-positive (meaning it can produce the enzyme catalase). Catalase converts hydrogen peroxide ( H 2 O 2 ) to water and oxygen. Catalase-activity tests are sometimes used to distinguish staphylococci from enterococci and streptococci . Previously, S. aureus

8060-445: The nostrils , and as a normal inhabitant of the lower reproductive tract of females. S. aureus can cause a range of illnesses, from minor skin infections, such as pimples , impetigo , boils , cellulitis , folliculitis , carbuncles , scalded skin syndrome , and abscesses , to life-threatening diseases such as pneumonia , meningitis , osteomyelitis , endocarditis , toxic shock syndrome , bacteremia , and sepsis . It

8184-513: The periodic table moving diagonally downward right from boron . They separate the electrical conductors (or metals, to the left) from the insulators (to the right). Devices made from semiconductor materials are the foundation of modern electronics, including radio, computers, telephones, etc. Semiconductor devices include the transistor , solar cells , diodes and integrated circuits . Solar photovoltaic panels are large semiconductor devices that directly convert light into electrical energy. In

8308-429: The sodium or potassium compounds tend to react with electrophiles at nitrogen-1, whereas the more covalent magnesium compounds ( indole Grignard reagents ) and (especially) zinc complexes tend to react at carbon 3 (see figure below). In analogous fashion, polar aprotic solvents such as DMF and DMSO tend to favour attack at the nitrogen, whereas nonpolar solvents such as toluene favour C3 attack. After

8432-474: The 2-aminofuran is the diene , whereas the indole is the dienophile . Indoles also undergo intramolecular [2+3] and [2+2] cycloadditions. Despite mediocre yields, intermolecular cycloadditions of indole derivatives have been well documented. One example is the Pictet-Spengler reaction between tryptophan derivatives and aldehydes , which produces a mixture of diastereomers , leading to reduced yield of

8556-497: The DNA, protects S. aureus from neutrophil extracellular trap -mediated killing. S. aureus also produces lipase to digest lipids, staphylokinase to dissolve fibrin and aid in spread, and beta-lactamase for drug resistance. Depending on the strain, S. aureus is capable of secreting several exotoxins , which can be categorized into three groups. Many of these toxins are associated with specific diseases. A secretion system

8680-453: The Earth's atmosphere. One example is Reinforced Carbon-Carbon (RCC), the light gray material that withstands reentry temperatures up to 1,510 °C (2,750 °F) and protects the nose cap and leading edges of Space Shuttle's wings. RCC is a laminated composite material made from graphite rayon cloth and impregnated with a phenolic resin . After curing at high temperature in an autoclave,

8804-508: The N–H proton, the hydrogen at C2 is the next most acidic proton on indole. Reaction of N -protected indoles with butyl lithium or lithium diisopropylamide results in lithiation exclusively at the C2 position. This strong nucleophile can then be used as such with other electrophiles. Bergman and Venemalm developed a technique for lithiating the 2-position of unsubstituted indole, as did Katritzky. Due to

8928-427: The aerospace industry, high performance materials used in the design of aircraft and/or spacecraft exteriors must have a high resistance to thermal shock. Thus, synthetic fibers spun out of organic polymers and polymer/ceramic/metal composite materials and fiber-reinforced polymers are now being designed with this purpose in mind. Because solids have thermal energy , their atoms vibrate about fixed mean positions within

9052-444: The atoms in a solid can take a variety of forms. For example, a crystal of sodium chloride (common salt) is made up of ionic sodium and chlorine , which are held together by ionic bonds . In diamond or silicon, the atoms share electrons and form covalent bonds . In metals, electrons are shared in metallic bonding . Some solids, particularly most organic compounds, are held together with van der Waals forces resulting from

9176-432: The biofilm matrix favor the formation of persister cells , which are highly antibiotic-resistant, dormant bacterial cells. S. aureus biofilms also have high resistance to host immune response. Though the exact mechanism of resistance is unknown, S. aureus biofilms have increased growth under the presence of cytokines produced by the host immune response. Host antibodies are less effective for S. aureus biofilm due to

9300-486: The body or on human tissue. It is commonly found with another pathogen, Candida albicans , forming multispecies biofilms. The latter is suspected to help S. aureus penetrate human tissue. A higher mortality is linked with multispecies biofilms. Staphylococcus aureus biofilm is the predominant cause of orthopedic implant-related infections, but is also found on cardiac implants, vascular grafts , various catheters , and cosmetic surgical implants. After implantation,

9424-511: The causal agents of mastitis in dairy cows . Its large polysaccharide capsule protects the organism from recognition by the cow's immune defenses . Staphylococcus aureus produces various enzymes such as coagulase (bound and free coagulases) which facilitates the conversion of fibrinogen to fibrin to cause clots which is important in skin infections. Hyaluronidase (also known as spreading factor) breaks down hyaluronic acid and helps in spreading it. Deoxyribonuclease , which breaks down

9548-663: The chemical bonds of the lignin before burning it out. One important property of carbon in organic chemistry is that it can form certain compounds, the individual molecules of which are capable of attaching themselves to one another, thereby forming a chain or a network. The process is called polymerization and the chains or networks polymers, while the source compound is a monomer. Two main groups of polymers exist: those artificially manufactured are referred to as industrial polymers or synthetic polymers (plastics) and those naturally occurring as biopolymers. Monomers can have various chemical substituents, or functional groups, which can affect

9672-467: The chemical properties of organic compounds, such as solubility and chemical reactivity, as well as the physical properties, such as hardness, density, mechanical or tensile strength, abrasion resistance, heat resistance, transparency, color, etc.. In proteins, these differences give the polymer the ability to adopt a biologically active conformation in preference to others (see self-assembly ). People have been using natural organic polymers for centuries in

9796-426: The control of bacterial virulence in S. aureus is growing. This can be facilitated by factors such as increased biofilm formation in the presence of increased levels of such small RNAs. For example, RNAIII , SprD , SprC, RsaE , SprA1, SSR42, ArtR, SprX , and Teg49 . Host neutrophils cause DNA double-strand breaks in S. aureus through the production of reactive oxygen species . For infection of

9920-419: The desired product. Indoles are susceptible to hydrogenation of the imine subunit to give indolines . Solid Solid is one of the four fundamental states of matter along with liquid , gas , and plasma . The molecules in a solid are closely packed together and contain the least amount of kinetic energy. A solid is characterized by structural rigidity (as in rigid bodies ) and resistance to

10044-543: The detection of extracellular and environmental indoles, are Salkowski , Kovács , Ehrlich’s reagent assays and HPLC . For intracellular indole detection and measurement genetically encoded indole-responsive biosensor is applicable. Indoles and their derivatives are promising against tuberculosis , malaria , diabetes , cancer , migraines , convulsions , hypertension , bacterial infections of methicillin-resistant Staphylococcus aureus ( MRSA ) and even viruses . Indole and its derivatives can also be synthesized by

10168-411: The early 1980s, Toyota researched production of an adiabatic ceramic engine with an operating temperature of over 6,000 °F (3,320 °C). Ceramic engines do not require a cooling system and hence allow a major weight reduction and therefore greater fuel efficiency. In a conventional metallic engine, much of the energy released from the fuel must be dissipated as waste heat in order to prevent

10292-514: The electron-rich nature of indole, it is easily oxidized . Simple oxidants such as N -bromosuccinimide will selectively oxidize indole 1 to oxindole ( 4 and 5 ). Only the C2–C3 pi bond of indole is capable of cycloaddition reactions . Intramolecular variants are often higher-yielding than intermolecular cycloadditions. For example, Padwa et al. have developed this Diels-Alder reaction to form advanced strychnine intermediates. In this case,

10416-404: The emergence of antibiotic-resistant strains, such as methicillin-resistant S. aureus (MRSA). The bacterium is a worldwide problem in clinical medicine . Despite much research and development , no vaccine for S. aureus has been approved. An estimated 21% to 30% of the human population are long-term carriers of S. aureus , which can be found as part of the normal skin microbiota , in

10540-487: The evasion of host immune system. Deletion of essX in S. aureus resulted in significantly reduced resistance to neutrophils and reduced virulence in murine skin and blood infection models. Altogether, T7SS and known secreted effector proteins are a strategy of pathogenesis by improving fitness against competitor S. aureus species as well as increased virulence via evading the innate immune system and optimising persistent infections. The list of small RNAs involved in

10664-578: The extreme hardness of zirconia is utilized in the manufacture of knife blades, as well as other industrial cutting tools. Ceramics such as alumina , boron carbide and silicon carbide have been used in bulletproof vests to repel large-caliber rifle fire. Silicon nitride parts are used in ceramic ball bearings, where their high hardness makes them wear resistant. In general, ceramics are also chemically resistant and can be used in wet environments where steel bearings would be susceptible to oxidation (or rust). As another example of ceramic applications, in

10788-474: The fitness of the bacterium containing it. Thus, S. aureus must make a trade-off to increase their success as a species, exchanging reduced virulence for increased drug resistance. Another barrier to evolution is the Sau1 Type I restriction modification (RM) system. This system exists to protect the bacterium from foreign DNA by digesting it. Exchange of DNA between the same lineage is not blocked, since they have

10912-527: The food, which is then ingested. Its incubation period lasts 30 minutes to eight hours, with the illness itself lasting from 30 minutes to 3 days. Preventive measures one can take to help prevent the spread of the disease include washing hands thoroughly with soap and water before preparing food. The Centers for Disease Control and Prevention recommends staying away from any food if ill, and wearing gloves if any open wounds occur on hands or wrists while preparing food. If storing food for longer than 2 hours, it

11036-433: The form of waxes and shellac , which is classified as a thermoplastic polymer. A plant polymer named cellulose provided the tensile strength for natural fibers and ropes, and by the early 19th century natural rubber was in widespread use. Polymers are the raw materials (the resins) used to make what are commonly called plastics. Plastics are the final product, created after one or more polymers or additives have been added to

11160-400: The formed indole-2-carboxylic acid. This has also been accomplished in a one-pot synthesis using microwave irradiation. Unlike most amines , indole is not basic : just like pyrrole , the aromatic character of the ring means that the lone pair of electrons on the nitrogen atom is not available for protonation. Strong acids such as hydrochloric acid can, however, protonate indole. Indole

11284-535: The glass-ceramic has a net coefficient of thermal expansion close to zero. This type of glass-ceramic exhibits excellent mechanical properties and can sustain repeated and quick temperature changes up to 1000 °C. Glass ceramics may also occur naturally when lightning strikes the crystalline (e.g. quartz) grains found in most beach sand . In this case, the extreme and immediate heat of the lightning (~2500 °C) creates hollow, branching rootlike structures called fulgurite via fusion . Organic chemistry studies

11408-673: The gold slabs (1064 °C); and metallic nanowires are much stronger than the corresponding bulk metals. The high surface area of nanoparticles makes them extremely attractive for certain applications in the field of energy. For example, platinum metals may provide improvements as automotive fuel catalysts , as well as proton exchange membrane (PEM) fuel cells. Also, ceramic oxides (or cermets) of lanthanum , cerium , manganese and nickel are now being developed as solid oxide fuel cells (SOFC). Lithium, lithium-titanate and tantalum nanoparticles are being applied in lithium-ion batteries. Silicon nanoparticles have been shown to dramatically expand

11532-455: The group, increasing its pathogenic ability. Thus, there is a need for a large number of mutations and acquisitions of mobile genetic elements. Another notable evolutionary process within the S. aureus species is its co-evolution with its human hosts. Over time, this parasitic relationship has led to the bacterium's ability to be carried in the nasopharynx of humans without causing symptoms or infection. This allows it to be passed throughout

11656-645: The heterogeneous antigen distribution, where an antigen may be present in some areas of the biofilm, but completely absent from other areas. Studies in biofilm development have shown to be related to changes in gene expression. There are specific genes that were found to be crucial in the different biofilm growth stages. Two of these genes include rocD and gudB, which encode for the enzyme's ornithine-oxo-acid transaminase and glutamate dehydrogenase , which are important for amino acid metabolism. Studies have shown biofilm development rely on amino acids glutamine and glutamate for proper metabolic functions. Protein A

11780-453: The host is contagious for another two weeks, and the overall illness lasts a few weeks. If untreated, though, the disease can be deadly. Deeply penetrating S. aureus infections can be severe. Skin infections are the most common form of S. aureus infection. This can manifest in various ways, including small benign boils , folliculitis , impetigo , cellulitis , and more severe, invasive soft-tissue infections. Staphylococcus aureus

11904-410: The human population, increasing its fitness as a species. However, only approximately 50% of the human population are carriers of S. aureus , with 20% as continuous carriers and 30% as intermittent. This leads scientists to believe that there are many factors that determine whether S. aureus is carried asymptomatically in humans, including factors that are specific to an individual person. According to

12028-556: The incoming light prior to capture. Here again, surface area of the nanoparticles (and thin films) plays a critical role in maximizing the amount of absorbed radiation. Many natural (or biological) materials are complex composites with remarkable mechanical properties. These complex structures, which have risen from hundreds of million years of evolution, are inspiring materials scientists in the design of novel materials. Their defining characteristics include structural hierarchy, multifunctionality and self-healing capability. Self-organization

12152-448: The ions and the electron cloud. The large number of free electrons gives metals their high values of electrical and thermal conductivity. The free electrons also prevent transmission of visible light, making metals opaque, shiny and lustrous . More advanced models of metal properties consider the effect of the positive ions cores on the delocalised electrons. As most metals have crystalline structure, those ions are usually arranged into

12276-496: The laminate is pyrolized to convert the resin to carbon, impregnated with furfural alcohol in a vacuum chamber, and cured/pyrolized to convert the furfural alcohol to carbon. In order to provide oxidation resistance for reuse capability, the outer layers of the RCC are converted to silicon carbide. Domestic examples of composites can be seen in the "plastic" casings of television sets, cell-phones and so on. These plastic casings are usually

12400-440: The major component is a metal are known as alloys . People have been using metals for a variety of purposes since prehistoric times. The strength and reliability of metals has led to their widespread use in construction of buildings and other structures, as well as in most vehicles, many appliances and tools, pipes, road signs and railroad tracks. Iron and aluminium are the two most commonly used structural metals. They are also

12524-418: The matrix properties. A synergism produces material properties unavailable from the individual constituent materials, while the wide variety of matrix and strengthening materials provides the designer with the choice of an optimum combination. Semiconductors are materials that have an electrical resistivity (and conductivity) between that of metallic conductors and non-metallic insulators. They can be found in

12648-408: The molecules in a gas are loosely packed. The branch of physics that deals with solids is called solid-state physics , and is the main branch of condensed matter physics (which also includes liquids). Materials science is primarily concerned with the physical and chemical properties of solids. Solid-state chemistry is especially concerned with the synthesis of novel materials, as well as

12772-734: The most abundant metals in the Earth's crust . Iron is most commonly used in the form of an alloy, steel, which contains up to 2.1% carbon , making it much harder than pure iron. Because metals are good conductors of electricity, they are valuable in electrical appliances and for carrying an electric current over long distances with little energy loss or dissipation. Thus, electrical power grids rely on metal cables to distribute electricity. Home electrical systems, for example, are wired with copper for its good conducting properties and easy machinability. The high thermal conductivity of most metals also makes them useful for stovetop cooking utensils. The study of metallic elements and their alloys makes up

12896-409: The ordered (or disordered) lattice. The spectrum of lattice vibrations in a crystalline or glassy network provides the foundation for the kinetic theory of solids . This motion occurs at the atomic level, and thus cannot be observed or detected without highly specialized equipment, such as that used in spectroscopy . Thermal properties of solids include thermal conductivity , which is the property of

13020-433: The polarization of the electronic charge cloud on each molecule. The dissimilarities between the types of solid result from the differences between their bonding. Metals typically are strong, dense, and good conductors of both electricity and heat . The bulk of the elements in the periodic table , those to the left of a diagonal line drawn from boron to polonium , are metals. Mixtures of two or more elements in which

13144-447: The presence of an S. aureus infection by the means of coagulase testing, which enables detection of an enzyme produced by the bacterium. Prior to the 1940s, S. aureus infections were fatal in the majority of patients. However, doctors discovered that the use of penicillin could cure S. aureus infections. Unfortunately, by the end of the 1940s, penicillin resistance became widespread amongst this bacterium population and outbreaks of

13268-499: The production of polycrystalline transparent ceramics such as transparent alumina and alumina compounds for such applications as high-power lasers. Advanced ceramics are also used in the medicine, electrical and electronics industries. Ceramic engineering is the science and technology of creating solid-state ceramic materials, parts and devices. This is done either by the action of heat, or, at lower temperatures, using precipitation reactions from chemical solutions. The term includes

13392-439: The purification of raw materials, the study and production of the chemical compounds concerned, their formation into components, and the study of their structure, composition and properties. Mechanically speaking, ceramic materials are brittle, hard, strong in compression and weak in shearing and tension. Brittle materials may exhibit significant tensile strength by supporting a static load. Toughness indicates how much energy

13516-414: The recipient genome by homologous recombination . S. aureus was found to be capable of natural genetic transformation, but only at low frequency under the experimental conditions employed. Further studies suggested that the development of competence for natural genetic transformation may be substantially higher under appropriate conditions, yet to be discovered. In humans, S. aureus can be present in

13640-631: The repressor of the main expolysaccharidic compound of the bacteria biofilm matrix) demonstrated that the 3'UTR binding to the 5' UTR can interfere with the translation initiation complex and generate a double stranded substrate for RNase III . The interaction is between the UCCCCUG motif in the 3'UTR and the Shine-Dalagarno region at the 5'UTR. Deletion of the motif resulted in IcaR repressor accumulation and inhibition of biofilm development. The biofilm formation

13764-582: The resistant strain began to occur. Staphylococcus aureus can be sorted into ten dominant human lineages. There are numerous minor lineages as well, but these are not seen in the population as often. Genomes of bacteria within the same lineage are mostly conserved, with the exception of mobile genetic elements . Mobile genetic elements that are common in S. aureus include bacteriophages, pathogenicity islands , plasmids , transposons , and staphylococcal cassette chromosomes. These elements have enabled S. aureus to continually evolve and gain new traits. There

13888-491: The same enzymes and the RM system does not recognize the new DNA as foreign, but transfer between different lineages is blocked. Staphylococcus aureus ( / ˌ s t æ f ɪ l ə ˈ k ɒ k ə s ˈ ɔːr i ə s , - l oʊ -/ , Greek σταφυλόκοκκος, "grape-cluster berry", Latin aureus , "golden") is a facultative anaerobic , gram-positive coccal (round) bacterium also known as "golden staph" and "oro staphira". S. aureus

14012-480: The science of identification and chemical composition . The atoms, molecules or ions that make up solids may be arranged in an orderly repeating pattern, or irregularly. Materials whose constituents are arranged in a regular pattern are known as crystals . In some cases, the regular ordering can continue unbroken over a large scale, for example diamonds, where each diamond is a single crystal . Solid objects that are large enough to see and handle are rarely composed of

14136-412: The secretion systems and has been hypothesised forming part of the translocation channel. The other proteins are EsaA, EssB, EssA, that are membrane proteins that function alongside EssC to mediate protein secretion. The exact mechanism of how substrates reach the cell surface is unknown, as is the interaction of the three membrane proteins with each other and EssC. T7 dependent effector proteins EsaD

14260-527: The solid state. The mechanical properties of materials describe characteristics such as their strength and resistance to deformation. For example, steel beams are used in construction because of their high strength, meaning that they neither break nor bend significantly under the applied load. Mechanical properties include elasticity , plasticity , tensile strength , compressive strength , shear strength , fracture toughness , ductility (low in brittle materials) and indentation hardness . Solid mechanics

14384-479: The storage capacity of lithium-ion batteries during the expansion/contraction cycle. Silicon nanowires cycle without significant degradation and present the potential for use in batteries with greatly expanded storage times. Silicon nanoparticles are also being used in new forms of solar energy cells. Thin film deposition of silicon quantum dots on the polycrystalline silicon substrate of a photovoltaic (solar) cell increases voltage output as much as 60% by fluorescing

14508-442: The structure, properties, composition, reactions, and preparation by synthesis (or other means) of chemical compounds of carbon and hydrogen , which may contain any number of other elements such as nitrogen , oxygen and the halogens: fluorine , chlorine , bromine and iodine . Some organic compounds may also contain the elements phosphorus or sulfur . Examples of organic solids include wood, paraffin wax , naphthalene and

14632-463: The surface of these devices becomes coated with host proteins, which provide a rich surface for bacterial attachment and biofilm formation. Once the device becomes infected, it must be completely removed, since S. aureus biofilm cannot be destroyed by antibiotic treatments. Current therapy for S. aureus biofilm-mediated infections involves surgical removal of the infected device followed by antibiotic treatment. Conventional antibiotic treatment alone

14756-402: The synthetic precursors for) the tryptophan-derived tryptamine alkaloids, which includes the neurotransmitter serotonin and the hormone melatonin , as well as the naturally occurring psychedelic drugs dimethyltryptamine and psilocybin . Other indolic compounds include the plant hormone auxin (indolyl-3-acetic acid, IAA ), tryptophol , the anti-inflammatory drug indomethacin , and

14880-508: The temperature is lowered, but remains finite. In a superconductor, however, the resistance drops abruptly to zero when the material is cooled below its critical temperature. An electric current flowing in a loop of superconducting wire can persist indefinitely with no power source. A dielectric , or electrical insulator, is a substance that is highly resistant to the flow of electric current. A dielectric, such as plastic, tends to concentrate an applied electric field within itself, which property

15004-415: The upper respiratory tract, gut mucosa, and skin as a member of the normal microbiota . However, because S. aureus can cause disease under certain host and environmental conditions, it is characterized as a "pathobiont". While S. aureus usually acts as a commensal bacterium , asymptomatically colonizing about 30% of the human population, it can sometimes cause disease. In particular, S. aureus

15128-400: The very young and very old. Without antibiotic treatment, S. aureus bacteremia has a case fatality rate around 80%. With antibiotic treatment, case fatality rates range from 15% to 50% depending on the age and health of the patient, as well as the antibiotic resistance of the S. aureus strain. Staphylococcus aureus is often found in biofilms formed on medical devices implanted in

15252-464: The wear plates of crushing equipment in mining operations. Most ceramic materials, such as alumina and its compounds, are formed from fine powders, yielding a fine grained polycrystalline microstructure that is filled with light-scattering centers comparable to the wavelength of visible light . Thus, they are generally opaque materials, as opposed to transparent materials . Recent nanoscale (e.g. sol-gel ) technology has, however, made possible

15376-414: Was differentiated from other staphylococci by the coagulase test . However, not all S. aureus strains are coagulase-positive and incorrect species identification can impact effective treatment and control measures. Natural genetic transformation is a reproductive process involving DNA transfer from one bacterium to another through the intervening medium, and the integration of the donor sequence into

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