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TSMC was founded in Taiwan in 1987 by Morris Chang as the world's first dedicated semiconductor foundry. It has long been the leading company in its field. [15] [16] When Chang retired in 2018, after 31 years of TSMC leadership, Mark Liu became chairman and C. C. Wei became Chief Executive.
- 73,090 (2022)
- US$73.67 billion (2022)
Alibaba Group Holding Limited, branded as Alibaba, is a Chinese multinational technology company specializing in e-commerce, retail, Internet, and technology. Founded on 28 June 1999 [1] in Hangzhou, Zhejiang, the company provides consumer-to-consumer (C2C), business-to-consumer (B2C), and business-to-business (B2B) sales services via Chinese ...
Principal component analysis ( PCA) is a linear dimensionality reduction technique with applications in exploratory data analysis, visualization and data preprocessing . The data is linearly transformed onto a new coordinate system such that the directions (principal components) capturing the largest variation in the data can be easily identified.
It was formed approximately 4.5 billion years ago, is a terrestrial planet and is the second smallest of the Solar System 's planets with a diameter of 6,779 km (4,212 mi). A Martian solar day ( sol) is 24.5 hours and a Martian solar year is 1.88 Earth years (687 Earth days). Mars has two small and irregular natural satellites: Phobos and Deimos.
- Operation
- History and Development
- Types
- Isocratic and Gradient Elution
- Parameters
- Applications
- See Also
- Further Reading
- External Links
The liquid chromatograph is complexand has sophisticated and delicate technology. In order to properly operate the system, there should be a minimum basis for understanding of how the device performs the data processing to avoid incorrect data and distorted results. HPLC is distinguished from traditional ("low pressure") liquid chromatographybecaus...
Prior to HPLC, scientists used benchtop column liquid chromatographic techniques. Liquid chromatographic systems were largely inefficient due to the flow rate of solvents being dependent on gravity. Separations took many hours, and sometimes days to complete. Gas chromatography (GC) at the time was more powerful than liquid chromatography (LC), how...
Partition chromatography
Partition chromatography was one of the first kinds of chromatography that chemists developed, and is barely used these days. The partition coefficient principle has been applied in paper chromatography, thin layer chromatography, gas phase and liquid–liquid separation applications. The 1952 Nobel Prize in chemistry was earned by Archer John Porter Martin and Richard Laurence Millington Synge for their development of the technique, which was used for their separation of amino acids. Partition...
Normal–phase chromatography
Normal–phase chromatography was one of the first kinds of HPLC that chemists developed, but has decreased in use over the last decades. Also known as normal-phase HPLC (NP-HPLC), this method separates analytes based on their affinity for a polar stationary surface such as silica; hence it is based on analyte ability to engage in polar interactions (such as hydrogen-bonding or dipole-dipole type of interactions) with the sorbent surface. NP-HPLC uses a non-polar, non-aqueous mobile phase (e.g....
Displacement chromatography
The use of displacement chromatography is rather limited, and is mostly used for preparative chromatography. The basic principle is based on a molecule with a high affinity for the chromatography matrix (the displacer) which is used to compete effectively for binding sites, and thus displace all molecules with lesser affinities.There are distinct differences between displacement and elution chromatography. In elution mode, substances typically emerge from a column in narrow, Gaussian peaks. W...
A separation in which the mobile phase composition remains constant throughout the procedure is termed isocratic (meaning constant composition). The word was coined by Csaba Horvathwho was one of the pioneers of HPLC. The mobile phase composition does not have to remain constant. A separation in which the mobile phase composition is changed during ...
Theoretical
The theory of high performance liquid chromatography-HPLC is basically the same as general chromatography theory. who received Nobel prize for it. The theory of chromatography has been used as the basis for system-suitability tests, as can be seen in the USP Pharmacopaeia,which are a set of quantitative criteria, which test the suitability of the HPLC system to the required analysis at any step of it. This relation is also represented as a normalized unit-less factor known as the retention fa...
Internal diameter
The internal diameter (ID) of an HPLC column is an important parameter. It can influence the detection response when reduced due to the reduced lateral diffusion of the solute band. It can also affect the separation selectivity, when flow rate and injection volumes are not scaled down or up proportionally to the smaller or larger diameter used, both in the isocratic and in gradient modes. It determines the quantity of analyte that can be loaded onto the column. Larger diameter columns are usu...
Particle size
Most traditional HPLC is performed with the stationary phase attached to the outside of small spherical silicaparticles (very small beads). These particles come in a variety of sizes with 5 µm beads being the most common. Smaller particles generally provide more surface area and better separations, but the pressure required for optimum linear velocity increases by the inverse of the particle diameter squared. According to the equations of the column velocity, efficiency and backpressure, redu...
Manufacturing
HPLC has many applications in both laboratory and clinical science. It is a common technique used in pharmaceutical development, as it is a dependable way to obtain and ensure product purity. While HPLC can produce extremely high quality (pure) products, it is not always the primary method used in the production of bulk drug materials. According to the European pharmacopoeia, HPLC is used in only 15.5% of syntheses. However, it plays a role in 44% of syntheses in the United States pharmacopoe...
Legal
This technique is also used for detection of illicit drugs in various samples. The most common method of drug detection has been an immunoassay. This method is much more convenient. However, convenience comes at the cost of specificity and coverage of a wide range of drugs, therefore, HPLC has been used as well as an alternative method. As HPLC is a method of determining (and possibly increasing) purity, using HPLC alone in evaluating concentrations of drugs was somewhat insufficient. Therefo...
Research
Similar assays can be performed for research purposes, detecting concentrations of potential clinical candidates like anti-fungal and asthma drugs.This technique is obviously useful in observing multiple species in collected samples, as well, but requires the use of standard solutions when information about species identity is sought out. It is used as a method to confirm results of synthesis reactions, as purity is essential in this type of research. However, mass spectrometry is still the m...
L. R. Snyder, J.J. Kirkland, and J. W. Dolan, Introduction to Modern Liquid Chromatography, John Wiley & Sons, New York, 2009.M.W. Dong, Modern HPLC for practicing scientists. Wiley, 2006.L. R. Snyder, J.J. Kirkland, and J. L. Glajch, Practical HPLC Method Development, John Wiley & Sons, New York, 1997.S. Ahuja and H. T. Rasmussen (ed), HPLC Method Development for Pharmaceuticals, Academic Press, 2007.HPLC Chromatography Principle, Application [Basic Note] – 2020. at Rxlalit.com[permanent dead link]Liquid Chromatography at CurlieTaiwan,[II][k] officially the Republic of China (ROC),[I][l] is a country[27] in East Asia.[o] It is located at the junction of the East and South China Seas in the northwestern Pacific Ocean, with the People's Republic of China (PRC) to the northwest, Japan to the northeast, and the Philippines to the south. The territories controlled by the ...
Aliexpress pavilion, Moscow Leningradsky railway station, 2016. AliExpress ( Chinese: 全球速卖通) is an online retail service based in China and owned by the Alibaba Group. [1] Launched in 2010, [2] [3] it is made up of small businesses in China and other locations, such as Singapore, that offer products to international online buyers.
