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Topic Review
Chemical Ionization
Chemical ionization (CI) is a soft ionization technique used in mass spectrometry. This was first introduced by Burnaby Munson and Frank H. Field in 1966. This technique is a branch of gaseous ion-molecule chemistry. Reagent gas molecules (often methane or ammonia) are ionized by electron ionization to form reagent ions, which subsequently react with analyte molecules in the gas phase to create analyte ions for analysis by mass spectrometry. Negative chemical ionization (NCI), charge-exchange chemical ionization, atmospheric-pressure chemical ionization (APCI) and atmospheric pressure photoionization (APPI) are some of the common variants of the technique. CI mass spectrometry finds general application in the identification, structure elucidation and quantitation of organic compounds as well as some utility in biochemical analysis. Samples to be analyzed must be in vapour form, or else (in the case of liquids or solids), must be vapourized before introduction into the source.
  • 705
  • 28 Nov 2022
Topic Review
Chemical Reaction Rate
The reaction rate for a reactant or product in a particular reaction is defined as the amount of the chemical that is formed or removed (in moles or mass units) per unit time per unit volume. Knowledge of these rates is essential in, among other disciplines, chemical engineering and environmental engineering. Chemical kinetics is the part of physical chemistry which studies reaction rates.
  • 580
  • 28 Nov 2022
Topic Review
Chemiluminescence Measurements of Premixed Flames Applying Abel Transform
The temperature field and chemiluminescence measurements of axisymmetric flame are obtained simultaneously in only one image. Digital Laser Speckle Displacement measures temperature fields, and direct image flame determines chemiluminescence values. Applying the Abel transform of axisymmetric objects for volume visualization requires smooth intensity profiles. Due to the nature of the experimental setup, direct image flame is corrupted with speckle noise and a crosstalk effect. These undesirable effects deteriorate the measurement results. Then, experimental data need crosstalk correction and speckle noise reduction to improve the measurements. 
  • 256
  • 29 Dec 2023
Biography
Chih-Kung Jen
Chih-Kung Jen (Chinese: 任之恭; pinyin: Rén Zhīgōng; August 15 or October 2, 1906 – November 19, 1995) was a Chinese physicist who emigrated to the U.S. and participated in some of the 20th century's major scientific, political and social developments in both the United States and China. Born in a mud house in a remote and largely illiterate village in China, he was awarded a scholarshi
  • 432
  • 09 Dec 2022
Topic Review
Chirality
A chiral phenomenon is one that is not identical to its mirror image (see the article on mathematical chirality). The spin of a particle may be used to define a handedness, or helicity, for that particle, which, in the case of a massless particle, is the same as chirality. A symmetry transformation between the two is called parity transformation. Invariance under parity transformation by a Dirac fermion is called chiral symmetry.
  • 511
  • 27 Oct 2022
Biography
Christopher Slowe
Christopher Brian Slowe (born November 8, 1978, Boston, MA) is an American businessman. He gained his PhD in Physics from Harvard, went on to co-found reddit, with Aaron Swartz, Alexis Ohanian and Steve Huffman. He later departed reddit and began work for Hipmunk, where he has been Chief Scientist since 2010. Slowe was awarded his Ph.D. in Physics from Harvard for his thesis "Experiments and
  • 442
  • 13 Dec 2022
Topic Review
Chromatin Architecture and Damage Response
DNA double-strand breaks (DSBs) have been recognized as the most serious lesions in irradiated cells. While several biochemical pathways capable of repairing these lesions have been identified, the mechanisms by which cells select a specific pathway for activation at a given DSB site remain poorly understood. The impact of chromatin and repair foci architecture on these mechanisms can be elucidated by super-resolution microscopy in combination with mathematical approaches of topology. These aspects are discussed in relation to state of the art knowledge of ionizing radiation induced damaging of cell nuclei and DNA repair.
  • 561
  • 20 Feb 2021
Topic Review
Circadian Regulation of Apolipoproteins in the Brain
The circadian rhythm is a 24 h internal clock within the body that regulates various factors, including sleep, body temperature, and hormone secretion. Circadian rhythm disruption is an important risk factor for many diseases including neurodegenerative illnesses. The central and peripheral oscillators’ circadian clock network controls the circadian rhythm in mammals. The clock genes govern the central clock in the suprachiasmatic nucleus (SCN) of the brain.
  • 172
  • 22 Dec 2023
Topic Review
Circinus
Circinus is a small, faint constellation located in the southern sky. Named after the Latin word for compass, it was first introduced in the 18th century by the French astronomer Nicolas Louis de Lacaille during his observations of the southern hemisphere. Despite its modest size, Circinus harbors several intriguing celestial objects, including a notable planetary nebula and multiple star systems of scientific interest.
  • 219
  • 08 Mar 2024
Topic Review
Classical Approaches at the Synchrotron Radiation Facilites
Synchrotron radiation sources are widely used in interdisciplinary research, generating an enormous amount of data while posing serious challenges to the storage, processing, and analysis capabilities of the large-scale scientific facilities worldwide.
  • 388
  • 15 May 2023
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