In analytical and organic chemistry, elution is the process of extracting one material from another by washing with a solvent. In a liquid chromatography experiment, for example, an analyte is adsorbed, or "bound to", an adsorbent in a liquid chromatography column; the adsorbent, a solid phase, is a powder, coated onto a solid support. Based on an adsorbent's composition, it can have varying affinities to "hold" onto other molecules—forming a thin film on its surface. Elution is the process of removing analytes from the adsorbent by running a solvent, called an "eluent", past the adsorbent/analyte complex; as the solvent molecules "elute", or travel down through the chromatography column, they can either pass by the adsorbent/analyte complex or they can displace the analyte by binding to the adsorbent in its place. After the solvent molecules displace the analyte, the analyte can be carried out of the column for analysis; this is why as the mobile phase passes out of the column, it flows into a detector or is collected for compositional analysis.
Predicting and controlling the order of elution is a key aspect of column chromatographic methods. An eluotropic series is listing of various compounds in order of eluting power for a given adsorbent; the “eluting power” of a solvent is a measure of how well the solvent can "pull" an analyte off the adsorbent to which it is attached. This happens when the eluent adsorbs onto the stationary phase, displacing the analyte; such series are useful for determining necessary solvents needed for chromatography of chemical compounds. Such a series progresses from non-polar solvents, such as n-hexane, to polar solvents such as methanol or water; the order of solvents in an eluotropic series depends both on the stationary phase as well as on the compound used to determine the order. The eluent or eluant is the "carrier" portion of the mobile phase, it moves the analytes through the chromatograph. In liquid chromatography, the eluent is the liquid solvent; the eluate is the analyte material. It includes both the analytes and solutes passing through the column, while the eluent is only the carrier.
The "elution time" of a solute is the time between the start of the separation and the time at which the solute elutes. In the same way, the elution volume is the volume of eluent required to cause elution. Under standard conditions for a known mix of solutes in a certain technique, the elution volume may be enough information to identify solutes. For instance, a mixture of amino acids may be separated by ion-exchange chromatography. Under a particular set of conditions, the amino acids will elute in the same order and at the same elution volume. Chromatography Desorption Gradient elution in high performance liquid chromatography Leaching Brown, Phillis. Advances in chromatography. CRC Press. P. 36. ISBN 0-8247-0509-2. Chemistry glossary Eluotropic series
Bio-Rad Laboratories, Inc. is a manufacturer of products for the life science research and clinical diagnostics markets. The company was founded in 1952 in Berkeley, California, by husband and wife team David and Alice Schwartz, both graduates of the University of California, Berkeley. Bio-Rad is based in Hercules and has operations worldwide. Bio-Rad’s life science products include instruments, consumables and content for the areas of cell biology, gene expression, protein purification, protein quantitation, drug discovery and manufacture, food safety, science education; these products are based on technologies to separate, identify and amplify biological materials such as antibodies, nucleic acids and bacteria. Bio-Rad’s diagnostic products and systems use a range of technologies and provide clinical information in the blood transfusion, diabetes monitoring and infectious disease testing markets; these products are used to support the diagnosis and treatment of diseases and other medical conditions.
Bio-Rad Laboratories was founded in 1952 by David Schwartz and his wife Alice, both recent graduates of the University of California, Berkeley. Bio-Rad expanded into the field of analytical and measuring instrument systems through internal research and development efforts and acquisitions in the late 1970s and 1980s. In 1999, Bio-Rad purchased Pasteur Sanofi Diagnostics; this strengthened the company’s position in the HIV and infectious disease diagnostic product market. In 2000, 2004, Bio-Rad divested its semiconductor, optoelectronic metrology, confocal microscopy product lines. In late 2007, Bio-Rad acquired Switzerland-based DiaMed Holding AG, enhancing Bio-Rad’s position in the immunohematology market. In January 2013, Bio-Rad purchased AbD Serotec, a division of MorphoSys AG; this added Serotec’s more than 15,000 antibodies and accessories to Bio-Rad’s portfolio of research and clinical diagnostic products. In 2011, Bio-Rad acquired a new technology droplet digital PCR, which extended the company's reach in the area of DNA amplification.
Droplet digital PCR allows scientists to distinguish rare sequences in tumors and measure copy number variation. Today the company has direct distribution channels in over 35 countries outside the United States through subsidiaries whose focus is sales, customer service and product distribution. In some locations outside and inside these 35 countries, sales efforts are supplemented by distributors and agents. Bioradiations is an online magazine created by Bio-Rad that offers researchers case studies, tips and topics related to Bio-Rad products and services. Bioradiations began as a print magazine, launched in 1965 and was in continuous publication until 2011. Content of the publication includes new product information and application notes describing experiments performed using Bio-Rad products as well as interviews with life science researchers; the site offers interactive content including product demonstrations in the form of system tours, podcasts etc. Laboratory equipment List of S&P 400 companies Official website Wall Street Journal profile
Surface-assisted laser desorption/ionization
Surface-assisted laser desorption/ionization is a soft laser desorption technique used for mass spectrometry analysis of biomolecules and small organic molecules. In its first embodiment it used graphite matrix. At present laser desorption/ionization methods using other inorganic matrices such as nanomaterials are regarded as SALDI variants; as an example, Titania nanotube arrays as a substrate can be used to detect small molecules. SALDI is used to detect proteins and protein-protein complexes. A related method named "ambient SALDI" -, a combination of conventional SALDI with ambient mass spectrometry incorporating the direct analysis real time ion source has been demonstrated. SALDI is considered one of the most important techniques in MS and has many applications. Sunner and Chen used graphite particles of 2-150 μm in size as a substrate and solutions of analytes in glycerol, they were able to analyze low molecular weight analytes and small proteins by soft ionization technique. They developed an approach called SALDI-MS, where a thin layer of activated carbon particles fixed on aluminum support in which the surface and the surface structure were critical in desorption and ionization Since the research was focusing on introducing novel nanomaterials as substrates, to enhance the sensitivity, broad the mass range and expanding the categories of samples that can be analyzed using this technique.
SALDI was introduced as a promising method with potential applications in systems biology metabolomics. The introduction of nanomaterials as SALDI substrates attracted researchers in analytical chemistry; such materials include carbon nanotubes, metallic nanoparticles like Ag, Pt, Au, nanostructured surfaces. This development of substrates allowed for further development of SALDI; the development of desorption/ionization on silicon -MS in particular, subsequently nanostructure-initiator mass spectrometry and nano-assisted laser desorption/ionization, has attracted the attention of analytical scientists. These methods have since become a benchmark for semiconductor-based SALDI research; the main principle of SALDI relies on a medium that absorbs energy from a laser and transfers the energy to the target sample. This class of techniques where the bulk of energy goes to the substrate instead of the sample molecules is known as soft ionization techniques; the development of SALDI started as a modification of matrix-assisted laser desorption/ionization.
The former technique suffered from ionization interference from the matrix molecules of MALDI. SALDI substituted an active surface of specific substrates made of inorganic components, for the organic matrix of MALDI. SALDI is a three-stage process; the first stage is concerned with mixing the samples with the substrate. In the second stage, the laser pulses are applied to the mix where the substrate absorbs the laser energy and transfers it to the sample molecules. In the final stage desorption and ionization occur and the potential difference accelerates produced ions into the mass analyzer; the substrate surface is playing a big role in adsorption and ionization of the analyte molecules. This role is affected by the chemical and physical properties of the substrate. Among these physical properties are the optical absorption coefficient, heat capacity and heat conductivity.1) The optical absorption coefficient: as this increases the ability of the substrate to absorb and generate more heat when absorb energy increases.
2) The heat capacity: as this decreases, the same amount of heat induces a larger temperature increase. 3) The heat conductivity: as this decreases, the substrate is better able to maintain the high temperature. There are three classes of nanomaterials that are utilized in SALDI-MS. Namely, the carbon-based, semiconductor-based and metallic-based; the term carbon nanotube refers to a cylinder with a rolled graphene sheet. CNT can be single walled or multi-walled; the SWNTs are perfect simulators of an ideal blackbody in the electromagnetic radiation ranging from the UV to far infrared. They exhibit better performance than former materials like super black; this makes the CNT's a desired material for laser mass spectrometry applications. That's why they attracted the researchers since discovery in the year 1991. Graphene is a type of popular carbon nanomaterial discovered in 2004, it has a large surface area that could attach the analyte molecules. On the other hand, the efficiency of desorption/ionization for analytes on a layer of graphene can be enhanced by its simple monolayer structure and unique electronic properties.
Polar compounds including amino acids, anticancer drugs, nucleosides can be analyzed. In addition, nonpolar molecules can be analyzed with high resolution and sensitivity due to the hydrophobic nature of graphene itself. Compared with a conventional matrix, graphene exhibites a high desorption/ionization efficiency for nonpolar compounds; the graphene substrate functions as a substrate to trap analytes and it transfers energy to the analytes upon laser irradiation, which allows for the analytes to be desorbed/ionized and the interference of matrix to be eliminated. It has been demonstrated that the use of graphene as a substrate material avoids the fragmentation of analytes and provides good reproducibility and a high salt tolerance. Porous silicon acted as an effective substrate for SALDI, its porous structure helped in trapping the analytes and its unique optical activity transferred the laser energy to the adsorbate
Baylor College of Medicine
Baylor College of Medicine, located in the Texas Medical Center in Houston, Texas, US, is a health sciences university. It includes Baylor College of Medicine; the school, located in the middle of the world's largest medical center, is part owner of Baylor St. Luke's Medical Center, part of the CHI St. Luke's Health system, has hospital affiliations with: Harris Health System, Texas Children's Hospital, The University of Texas MD Anderson Cancer Center, Memorial Hermann – The Institute for Rehabilitation and Research, Menninger Clinic, the Michael E. DeBakey Veterans Affairs Medical Center and Children's Hospital of San Antonio; the medical school has been considered in the top tier of programs in the country, is noted for having the lowest tuition among all private medical schools in the US. Its Graduate School of Biomedical Sciences is among the top 25 graduate schools in the United States. Within the School of Allied Health Sciences, the Nurse anesthetist program ranks 2nd and the physician assistant program ranks 13th.
A program in Orthotics and Prosthetics began with 18 students in the first class. The National School of Tropical Medicine is the only school in the nation dedicated to patient care, research and policy related to neglected tropical diseases. On June 21, 2010, Dr. Paul Klotman was named as the President and CEO of the Baylor College of Medicine. In January 2014, the College and CHI St. Luke's became joint owners of Baylor St. Luke's Medical Center; the school was formed in Dallas, Texas by a small group of Baylor University alumni physicians who aimed to improve medical practice in North Texas. Called the University of Dallas Medical Department, the school opened its doors October 30, 1900, with 81 students. Dr. Albert Ferdinand Beddoe, A. B. M. D. was a co-founder, alongside Samuel Hollingsworth Stout, who served as its founding dean from 1902 to 1903. Meanwhile, Beddoe became a professor, he built up the free clinic in connection with Baylor hospital. In 1903, an alliance with Baylor University in Waco was formed and the name was changed to Baylor University College of Medicine.
By 1918, Baylor University College of Medicine was the only private medical school in Texas. The M. D. Anderson Foundation invited Baylor to join the newly formed Texas Medical Center in Houston in 1943; the school opened in the medical center July 12, 1943, in a converted Sears, Roebuck & Co. warehouse, with 131 students. Four years Baylor moved to its present site in the Roy and Lillie Cullen Building, the first building completed in the Texas Medical Center. In 1948, Michael E. DeBakey joined the faculty as chair of the Department of Surgery, the following year, the Graduate School of Biomedical Sciences was established. Baylor's rise in prominence began in the 1950s when DeBakey's surgical techniques garnered international attention. In the 1960s, the college underwent its first major expansion. In 1969, the college separated from Baylor University and became an independent institution, which allowed it access to federal research funding, changing its name to Baylor College of Medicine; that same year, BCM negotiated with the Texas Legislature to double its class size in order to increase the number of physicians in Texas.
In 2005, Baylor College of Medicine began building a hospital and clinic, to be called the Baylor Clinic and Hospital, slated to open in 2011. In 2009, the college postponed construction for financial reasons, with the outer shell of the hospital completed but the interiors remaining unfinished. In March 2012, BCM decided to convert the building to an outpatient clinic center. In 2009, BCM entered into discussions with Rice University regarding a potential merger between the two Houston institutions. After extensive meetings, the boards at both institutions decided that each school would remain an independent. In 2010, Baylor University entered into talks with BCM to strengthening ties to each other. In January 2014, the BCM and CHI St. Luke's announced they would become joint owners of Baylor St. Luke's Medical Center, a hospital at the Texas Medical Center. A completed hospital building on the BCM–McNair Campus is slated to open in 2015 and will become BCM's acute-care hospital and main medical teaching facility.
Each year the medical school matriculates around 185 students, around 75% of whom are Texas residents. Baylor College of Medicine is the least expensive private medical school in the country, it is one of the few medical schools in the United States, structured with an accelerated 1.5 year preclinical curriculum. Baylor College of Medicine is one of only 45 medical institutions in the United States to offer a Medical Scientist Training Program; this federally sponsored and competitive program allows exceptionally well qualified students to study for a combined MD and PhD in a medical science to be earned in 7–9 total years. 8–12 students matriculate into this program per year, receive free tuition in addition to a stipend of $29,000 per academic year. The Baylor College of Medicine Graduate School of Biomedical Sciences ranks 25th for best Ph. D. program in the biological sciences. Overall, in 2018 BCM ranked 20th in terms of research funding from the National Institutes of Health based on rankings done by the Blue Ridge Institute.
Baylor ranked in the top 20 in eight specialty areas, including number one in the nation for Gene
The velocity of an object is the rate of change of its position with respect to a frame of reference, is a function of time. Velocity is equivalent to a specification of an object's direction of motion. Velocity is a fundamental concept in kinematics, the branch of classical mechanics that describes the motion of bodies. Velocity is a physical vector quantity; the scalar absolute value of velocity is called speed, being a coherent derived unit whose quantity is measured in the SI as metres per second or as the SI base unit of. For example, "5 metres per second" is a scalar. If there is a change in speed, direction or both the object has a changing velocity and is said to be undergoing an acceleration. To have a constant velocity, an object must have a constant speed in a constant direction. Constant direction constrains the object to motion in a straight path thus, a constant velocity means motion in a straight line at a constant speed. For example, a car moving at a constant 20 kilometres per hour in a circular path has a constant speed, but does not have a constant velocity because its direction changes.
Hence, the car is considered to be undergoing an acceleration. Speed describes only how fast an object is moving, whereas velocity gives both how fast it is and in which direction the object is moving. If a car is said to travel at 60 km/h, its speed has been specified. However, if the car is said to move at 60 km/h to the north, its velocity has now been specified; the big difference can be noticed. When something moves in a circular path and returns to its starting point, its average velocity is zero but its average speed is found by dividing the circumference of the circle by the time taken to move around the circle; this is because the average velocity is calculated by only considering the displacement between the starting and the end points while the average speed considers only the total distance traveled. Velocity is defined as the rate of change of position with respect to time, which may be referred to as the instantaneous velocity to emphasize the distinction from the average velocity.
In some applications the "average velocity" of an object might be needed, to say, the constant velocity that would provide the same resultant displacement as a variable velocity in the same time interval, v, over some time period Δt. Average velocity can be calculated as: v ¯ = Δ x Δ t; the average velocity is always equal to the average speed of an object. This can be seen by realizing that while distance is always increasing, displacement can increase or decrease in magnitude as well as change direction. In terms of a displacement-time graph, the instantaneous velocity can be thought of as the slope of the tangent line to the curve at any point, the average velocity as the slope of the secant line between two points with t coordinates equal to the boundaries of the time period for the average velocity; the average velocity is the same as the velocity averaged over time –, to say, its time-weighted average, which may be calculated as the time integral of the velocity: v ¯ = 1 t 1 − t 0 ∫ t 0 t 1 v d t, where we may identify Δ x = ∫ t 0 t 1 v d t and Δ t = t 1 − t 0.
If we consider v as velocity and x as the displacement vector we can express the velocity of a particle or object, at any particular time t, as the derivative of the position with respect to time: v = lim Δ t → 0 Δ x Δ t = d x d t. From this derivative equation, in the one-dimensional case it can be seen that the area under a velocity vs. time is the displacement, x. In calculus terms, the integral of the velocity function v is the displacement function x. In the figure, this corresponds to the yellow area under the curve labeled s. X = ∫ v d t. Since the derivative of the position with respect to time gives the change in position divided by the change in time, velocity is measured in metres per second. Although the concept of an instantaneous velocity might at first seem counter-intuitive, it
A biomarker, or biological marker is a measurable indicator of some biological state or condition. Biomarkers are measured and evaluated to examine normal biological processes, pathogenic processes, or pharmacologic responses to a therapeutic intervention. Biomarkers are used in many scientific fields. In medicine, a biomarker can be a traceable substance, introduced into an organism as a means to examine organ function or other aspects of health. For example, rubidium chloride is used as a radioactive isotope to evaluate perfusion of heart muscle, it can be a substance whose detection indicates a particular disease state, for example, the presence of an antibody may indicate an infection. More a biomarker indicates a change in expression or state of a protein that correlates with the risk or progression of a disease, or with the susceptibility of the disease to a given treatment. One example of a used biomarker in medicine is prostate-specific antigen; this marker can be measured as a proxy of prostate size with rapid changes indicating cancer.
The most extreme case would be to detect mutant proteins as cancer specific biomarkers through Selected reaction monitoring, since mutant proteins can only come from an existing tumor, thus providing the best specificity for medical purposes. Biomarkers used for personalized medicine are categorized as either prognostic or predictive. An example is KRAS, an oncogene that encodes a GTPase involved in several signal transduction pathways. Prognostic biomarkers indicate the likelihood of patient outcome regardless of a specific treatment. Predictive biomarkers are used to help optimize ideal treatments, indicates the likelihood of benefiting from a specific therapy. Biomarkers for precision oncology are utilized in the molecular diagnostics of chronic myeloid leukemia, colon and lung cancer, in melanoma. Proof of concept Previously used to identify the specific characteristics of the biomarker, this step is essential for doing an in situ validation of these benefits. A large number of candidates must be tested to select the most relevant ones.
Experimental validation This step allows the development of the most adapted protocol for routine use of the biomarker. It is possible to confirm the relevance of the protocol with various methods and to define strata based on the results. Analytical performances validation One of the most important steps, it serves to identify specific characteristics of the candidate biomarker before developing a routine test. Several parameters are considered including: sensitivity specificity robustness accuracy reproducibilityProtocol standardization This optimizes the validated protocol for routine use, including analysis of the critical points by scanning the entire procedure to identify and control the potential risks. In cell biology, a biomarker is a molecule that allows the detection and isolation of a particular cell type. In genetics, a biomarker is a DNA sequence that causes disease or is associated with susceptibility to disease, they can be used to create genetic maps. A biomarker can be any kind of molecule indicating the existence, past or present, of living organisms.
In the fields of geology and astrobiology, versus geomarkers, are known as biosignatures. The term biomarker is used to describe biological involvement in the generation of petroleum. TBI biomarkers might be detected in biofluid in different post-injury time. See graph. Biomarkers are used to indicate an exposure to or the effect of xenobiotics which are present in the environment and in organisms; the biomarker may be an external substance itself, or a variant of the external substance processed by the body that can be quantified. The widespread use of the term "biomarker" dates back to as early as 1980; the term "biological marker" was introduced in 1950s. In 1998, the National Institutes of Health Biomarkers Definitions Working Group defined a biomarker as "a characteristic, objectively measured and evaluated as an indicator of normal biological processes, pathogenic processes, or pharmacologic responses to a therapeutic intervention."
Blood is a body fluid in humans and other animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells. In vertebrates, it is composed of blood cells suspended in blood plasma. Plasma, which constitutes 55% of blood fluid, is water, contains proteins, mineral ions, carbon dioxide, blood cells themselves. Albumin is the main protein in plasma, it functions to regulate the colloidal osmotic pressure of blood; the blood cells are red blood cells, white blood cells and platelets. The most abundant cells in vertebrate blood are red blood cells; these contain hemoglobin, an iron-containing protein, which facilitates oxygen transport by reversibly binding to this respiratory gas and increasing its solubility in blood. In contrast, carbon dioxide is transported extracellularly as bicarbonate ion transported in plasma. Vertebrate blood is bright red when its hemoglobin is oxygenated and dark red when it is deoxygenated.
Some animals, such as crustaceans and mollusks, use hemocyanin to carry oxygen, instead of hemoglobin. Insects and some mollusks use a fluid called hemolymph instead of blood, the difference being that hemolymph is not contained in a closed circulatory system. In most insects, this "blood" does not contain oxygen-carrying molecules such as hemoglobin because their bodies are small enough for their tracheal system to suffice for supplying oxygen. Jawed vertebrates have an adaptive immune system, based on white blood cells. White blood cells help to resist parasites. Platelets are important in the clotting of blood. Arthropods, using hemolymph, have hemocytes as part of their immune system. Blood is circulated around the body through blood vessels by the pumping action of the heart. In animals with lungs, arterial blood carries oxygen from inhaled air to the tissues of the body, venous blood carries carbon dioxide, a waste product of metabolism produced by cells, from the tissues to the lungs to be exhaled.
Medical terms related to blood begin with hemo- or hemato- from the Greek word αἷμα for "blood". In terms of anatomy and histology, blood is considered a specialized form of connective tissue, given its origin in the bones and the presence of potential molecular fibers in the form of fibrinogen. Blood performs many important functions within the body, including: Supply of oxygen to tissues Supply of nutrients such as glucose, amino acids, fatty acids Removal of waste such as carbon dioxide and lactic acid Immunological functions, including circulation of white blood cells, detection of foreign material by antibodies Coagulation, the response to a broken blood vessel, the conversion of blood from a liquid to a semisolid gel to stop bleeding Messenger functions, including the transport of hormones and the signaling of tissue damage Regulation of core body temperature Hydraulic functions Blood accounts for 7% of the human body weight, with an average density around 1060 kg/m3 close to pure water's density of 1000 kg/m3.
The average adult has a blood volume of 5 litres, composed of plasma and several kinds of cells. These blood cells consist of erythrocytes and thrombocytes. By volume, the red blood cells constitute about 45% of whole blood, the plasma about 54.3%, white cells about 0.7%. Whole blood exhibits non-Newtonian fluid dynamics. If all human hemoglobin were free in the plasma rather than being contained in RBCs, the circulatory fluid would be too viscous for the cardiovascular system to function effectively. One microliter of blood contains: 4.7 to 6.1 million, 4.2 to 5.4 million erythrocytes: Red blood cells contain the blood's hemoglobin and distribute oxygen. Mature red blood cells lack a nucleus and organelles in mammals; the red blood cells are marked by glycoproteins that define the different blood types. The proportion of blood occupied by red blood cells is referred to as the hematocrit, is about 45%; the combined surface area of all red blood cells of the human body would be 2,000 times as great as the body's exterior surface.
4,000–11,000 leukocytes: White blood cells are part of the body's immune system. The cancer of leukocytes is called leukemia. 200,000 -- 500,000 thrombocytes: Also called platelets. Fibrin from the coagulation cascade creates a mesh over the platelet plug. About 55% of blood is blood plasma, a fluid, the blood's liquid medium, which by itself is straw-yellow in color; the blood plasma volume totals of 2.7–3.0 liters in an average human. It is an aqueous solution containing 92% water, 8% blood plasma proteins, trace amounts of other materials. Plasma circulates dissolved nutrients, such as glucose, amino acids, fatty acids, removes waste products, such as carbon dioxide and lactic acid. Other important components include: Serum albumin Blood-clotting factors Immunoglobulins lipoprotein particles Various