A practical reference on electron paramagnetic resonance: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-03-29. Anything still debated is marked as such rather than presented as settled.
Stability of GHK-Cu in solution depends on pH, temperature, buffer composition, and oxygen exposure. The copper center can undergo reduction or dissociation, especially in the presence of strong metal chelators such as EDTA. Aqueous solutions are often prepared fresh or stored frozen to limit degradation. Lyophilized solid is more stable than liquid formulations, but it can absorb moisture and should be kept dry. Light exposure may also affect copper complexes, though the effect is often modest.
Purity assessment typically involves high-performance liquid chromatography for the peptide and atomic spectroscopy for copper content. The ratio of copper to peptide is a key quality parameter; a value near one indicates proper stoichiometry. Impurities can include free peptide, copper salts, and truncated sequences from synthesis. Because the complex is dynamic, sample preparation and mobile-phase conditions can shift the observed species. Reported purity values therefore depend on the analytical method and should be interpreted with that context.
Practical handling notes centre on limiting exposure to water, oxygen, and repeated temperature cycling. Weighed powder is often equilibrated to room temperature before opening to avoid condensation on the solid. Working solutions are typically divided into single-use aliquots and frozen rather than stored refrigerated for long periods. Reported shelf lives vary widely between laboratories, and no single set of conditions is universally treated as a reference standard, which complicates direct comparison of published stability figures.
Solutions of GHK-Cu respond strongly to pH, redox conditions, and the presence of competing chelators such as EDTA. Below roughly pH 4 the copper tends to dissociate, because the amide nitrogen donors become protonated and can no longer coordinate. Strongly alkaline conditions instead favour hydrolysis and precipitation of copper hydroxide. Dissolved oxygen and light accelerate breakdown of the peptide backbone, and the copper released during that process can catalyse further oxidation, so dry, cold, dark storage is the usual recommendation.
Routine characterisation relies on reversed-phase high-performance liquid chromatography for peptide purity, paired with mass spectrometry for identity confirmation. Ultraviolet-visible spectroscopy detects the metal centre through its absorption band in the visible region, and inductively coupled plasma mass spectrometry quantifies total copper so that a metal-to-peptide ratio can be calculated. Amino acid analysis confirms the expected residue composition. Together these techniques establish concentration, identity, and stoichiometry, but none of them directly reports biological activity.
| Property | Value | Notes |
|---|---|---|
| Typical storage temperature | -20 °C or below | For lyophilized solid; solutions are less stable |
| Common analytical method | RP-HPLC with UV detection | For peptide purity; copper quantified separately |
| Copper quantification | ICP-MS or atomic absorption | Determines metal content and stoichiometry |
| Aqueous stability | Hours to days at room temperature | Depends on pH, buffer, and chelators |
| Color in solution | Blue | Absorption near 600 nm indicates Cu(II) coordination |
Analytical verification commonly relies on high-performance liquid chromatography for purity assessment and mass spectrometry for identity confirmation. Spectroscopic methods such as UV-visible absorption and electron paramagnetic resonance can probe the metal centre itself, since the d9 configuration of copper(II) produces characteristic signals. Elemental analysis or plasma-based techniques quantify copper content. Because each method reports a different aspect of the same sample, purity figures are most meaningful when the technique and its detection wavelength are stated alongside the value.
Stability of the complex in solution depends on pH, temperature, and the presence of competing ligands. It is generally described as more resistant to breakdown than the metal-free chain, since coordination reduces susceptibility to enzymatic attack. Oxidation and hydrolysis can nevertheless proceed over time in aqueous media. Storage guidance in laboratory settings commonly involves refrigeration, protection from light, and avoidance of strongly alkaline conditions. Published data on long-term behaviour vary considerably and depend on the specific matrix.
Identity and purity are assessed mainly by reversed-phase high-performance liquid chromatography with ultraviolet detection, often paired with mass spectrometry to confirm the expected mass. Copper content is measured separately by inductively coupled plasma optical emission spectrometry or atomic absorption spectroscopy, because the peptide assay alone does not establish the metal-to-peptide ratio. Visible spectroscopy provides a rapid check on complex integrity through the absorption band in the visible region. Agreement between the peptide assay and the copper assay is the practical test of whether a sample is the intended complex rather than a mixture.
Aqueous solutions of GHK-Cu are less stable than the dry powder. The peptide backbone is vulnerable to hydrolysis at extreme pH, and copper can be stripped from the complex by strong chelating agents such as EDTA or citrate. Oxidising agents and high concentrations of ascorbic acid can reduce copper(II) and change the complex, which is one reason formulators often keep such ingredients in separate phases. How quickly these changes occur under real storage conditions depends on pH, buffer, temperature and packaging, and quantitative data on the subject are limited.
Dry material is normally held cold, commonly at -20 °C for long-term storage and 2 to 8 °C for working quantities, protected from light and moisture. Vials should be allowed to reach room temperature before opening so that condensation does not form on the powder. In liquid formulations the complex is generally kept near neutral to slightly acidic pH, because strongly alkaline conditions favour precipitation of copper hydroxide. Antioxidants or chelate-stabilising excipients are often added, though the specific approaches are proprietary and rarely published in detail.
RBR (Reduced Bit Rate): 1.62 Gbit/s bandwidth per lane (162 MHz link symbol rate) HBR (High Bit Rate): 2.70 Gbit/s bandwidth per lane (270 MHz link symbol rate) HBR2 (High Bit Rate 2): 5.40 Gbit/s bandwidth per lane (540 MHz link symbol rate), introduced in DP 1.2 HBR3 (High Bit Rate 3): 8.10 Gbit/s bandwidth per lane (810 MHz link symbol rate), introduced in DP 1.3 DisplayPort 2.0 uses 128b/132b encoding; each group of 132 transmitted bits represents 128 bits of data. This scheme has an efficiency of 96.96%. In addition, a small amount of overhead is added for the link layer control packet and other miscellaneous operations, resulting in an overall efficiency of ≈96.7%. The following transmission modes are added in DP 2.0:
Activation of presynaptic dopamine autoreceptors by dihydroergocriptine leads to reduced dopamine receptor turnover and indirect antioxidant effects. In particular, further activation of intracellular kinase systems due to dopamine agonists are hypothesized to lead to antiapoptotic effects that also help in halting and slowing the disease progression. This may also contribute to prevention of development of motor fluctuations, though more research is needed. Modern agonists like dihydroergocryptine typically cost two to three times more than levodopa therapy. More health economics assessments may be needed to determine whether the initial increased costs of the agonists are offset by less patients needing surgery in later stages of the disease.
=== Duration and exclusivity === Numerous health organizations, including, but not limited to, the CDC, WHO, National Health Service, Canadian Pediatric Society, American Academy of Pediatrics, and American Academy of Family Physicians, recommend breastfeeding exclusively for six months following birth, unless medically contraindicated. Exclusive breastfeeding is defined as "an infant's consumption of human milk with no supplementation of any type (no water, no juice, no nonhuman milk and no foods) except for vitamins, minerals and medications." Supplementation with human donor breastmilk may be indicated in some specific cases, as discussed below. After solids are introduced at around six months of age, continued breastfeeding is recommended. The American Academy of Pediatrics recommends that babies be breastfed at least until 12 months, or longer if both the mother and child wish. The World Health Organization's guidelines recommend "continue[d] frequent, on-demand breastfeeding until two years of age or beyond. The American Academy of Pediatrics policy statement also supports continued breastfeeding to 2 years and older, depending on the mother and child. Extended breastfeeding means breastfeeding after the age of 12 or 24 months, depending on the source. In Western countries such as the United States, Canada, and Great Britain, extended breastfeeding is relatively uncommon and can provoke criticism. Globally exclusive breastfeeding rose from 37.0% to 47.4% between 2012 and 2024;.
== Personal life == In 1915, Boyd Orr married Elizabeth Pearson Callum, whom he had met as a teenager in West Kilbride. They had three children: Elizabeth Joan (born 1916), Helen Anne (born 1919) and Donald Noel (1921–1942). His son was killed on active service during the Second World War.
Gate of Flesh (Japanese: 肉體の門, Hepburn: Nikutai no mon) is a 1964 Japanese film based on a novel by Taijiro Tamura and directed by Seijun Suzuki. The first of Suzuki's "flesh trilogy" (followed by Story of a Prostitute and Carmen from Kawachi), the series is considered the "crowning achievement" of his period working at the production house Nikkatsu. The film is viewed as a direct and allegorical critique of Japan's Occupation and subsequent development, which rather than breaking with the country's pre-war militaristic, authoritarian social structures only sees their reconstitution in the post-war period.
Sources: en.wikipedia.org
The methionine-derivative S-adenosylmethionine (rSAM) is a cofactor that serves mainly as a methyl donor. rSAM is composed of an adenosyl molecule (via 5′ carbon) attached to the sulfur of methionine. It is a sulfonium cation that releases a methyl radical upon reduction.
Due to its application in the manufacturing of illicit substances, it is listed in the Table II precursor under the United Nations Convention Against Illicit Traffic in Narcotic Drugs and Psychotropic Substances as well as substances such as acetone, toluene and sulfuric acid.
== Notable environmental chemists == Joan Berkowitz Paul Crutzen (Nobel Prize in Chemistry, 1995) Philip Gschwend Alice Hamilton John M. Hayes Charles David Keeling Ralph Keeling Mario Molina (Nobel Prize in Chemistry, 1995) James J. Morgan Clair Patterson Roger Revelle Sherry Roland (Nobel Prize in Chemistry, 1995) Robert Angus Smith Susan Solomon Werner Stumm Ellen Swallow Richards Hans Suess John Tyndall
On March 19, 2012, UPS announced that it intended to acquire TNT Express for $6.8 billion, in a move to help expand its presence in European and Asian markets. However, the deal fell through in January 2013, after it was announced that UPS had failed to obtain permission from the European Commission and as such had been blocked on competition grounds. In February 2012, UPS acquired Brussels-based company Kiala that provides e-commerce retailers the option to have goods delivered to a conventional retail location. In 2018, The Wall Street Journal reported that UPS's operations were hampered by its outdated 20th-century technology, lagging behind its competitors. In May 2019, UPS launched a partnership with autonomous trucking startup TuSimple to carry cargo across Phoenix, Arizona, and Tucson, Arizona. In October 2019, UPS won the approval of the Federal Aviation Administration to fly drones. The certification will allow UPS to deliver health care supplies using a fleet of drones. On January 29, 2020, UPS announced it was investing in UK start-up Arrival and ordering 10,000 Generation 2 electric vehicles as a step towards a cleaner, more high-tech fleet. The deal ran from 2020 until 2024 and was reported to be worth more than $400 million. In March 2020, the company appointed Carol Tomé to succeed David Abney as its chief executive officer. It was viewed as a move to steer the parcel delivery company through the turbulence of trade wars, technological disruption and the risk of a pandemic-induced recession.
It was during this time period that President Roosevelt made his first visit to Mexico in April 1943, in what was an exchange visit, as President Ávila Camacho was also visiting the US. Both met in the city of Monterrey, specifically at the Palacio de Gobierno, and one of the topics covered there was Mexican participation in the war. These meetings demonstrated that never before had such a close and positive bilateral relationship been formed between the two countries, thus resolving an era of hostility that began a century ago.
Sources: en.wikipedia.org
== Technology == OpenELIS is web-based, with a Java/Spring backend and a React front end, and is deployed using Docker-based containerised infrastructure. It provides interoperability through the HL7 FHIR R4 standard, for which the project publishes a FHIR implementation guide, alongside ASTM and HL7 v2 interfaces for laboratory analyzers and LOINC and SNOMED terminology, and is aligned with the OpenHIE architecture for exchange with electronic medical records and health information exchanges. It is released under the Mozilla Public License 2.0. OpenELIS is recognised as a Digital Square "global good for health" and is listed as a digital public good by the Digital Public Goods Alliance.
== Genetics == Contrary to bacteria and fungi, most plant metabolic pathways are not grouped into biosynthetic gene clusters, but instead are scattered as individual genes. Some exceptions have been discovered: steroidal glycoalkaloids in Solanum, polyketides in Pooideae, benzoxazinoids in Zea mays, triterpenes in Avena sativa, Cucurbitaceae, Arabidopsis, and momilactone diterpenes in Oryza sativa.
Mitragynine is an indole-based alkaloid and is one of the main psychoactive constituents in the Southeast Asian plant Mitragyna speciosa, commonly known as kratom. It has also been researched for its use to potentially manage symptoms of opioid withdrawal. It is a partial agonist of the μ-opioid receptors; and as such can produce effects similar to those of classic opioids such as morphine. Mitragynine is the most abundant active alkaloid in kratom. In Thai varieties of kratom, mitragynine is the most abundant component (up to 66% of total alkaloids), while 7-hydroxymitragynine (7-OH-MIT) is a minor constituent (up to 2% of total alkaloid content). In Malaysian kratom varieties, mitragynine is present at lower concentration (12% of total alkaloids). Total alkaloid concentration in dried leaves ranges from 0.5–1.5%. Such preparations are orally consumed and typically involve dried kratom leaves which are brewed into tea or ground and placed into capsules.
=== Antifungal === One of the main uses of amphotericin B is treating a wide range of systemic fungal infections. Due to its extensive side effects, it is often reserved for severe infections in critically ill or immunocompromised patients. It is considered first line therapy for invasive mucormycosis infections, cryptococcal meningitis, and certain aspergillus and candidal infections. It has been a highly effective drug for over fifty years in large part because it has a low incidence of drug resistance in the pathogens it treats. This is because amphotericin B resistance requires sacrifices on the part of the pathogen that make it susceptible to the host environment, and too weak to cause infection.
The rotation of plane polarized light by chiral substances was first observed by Jean-Baptiste Biot in 1812, and gained considerable importance in the sugar industry, analytical chemistry, and pharmaceuticals. Louis Pasteur deduced in 1848 that this phenomenon has a molecular basis. The term chirality itself was coined by Lord Kelvin in 1894. Individual enantiomers or diastereomers of a compound were formerly called optical isomers due to their distinct optical properties. At one time, chirality was thought to be restricted to organic chemistry, but this misconception was overthrown by the resolution of a purely inorganic compound, a cobalt complex called hexol, by Alfred Werner in 1911. In the early 1970s, various groups established that the human olfactory organ is capable of distinguishing chiral compounds.
Sources: en.wikipedia.org
Peptide content is usually measured by reverse-phase high-performance liquid chromatography, while copper is measured by atomic spectroscopy. Mass spectrometry can confirm the peptide identity and detect copper adducts. Combining these methods gives a more complete picture.
pH, temperature, oxygen, light, and the presence of metal chelators all influence stability. Strong chelators can strip copper from the peptide, and reducing agents can change the copper oxidation state. Lyophilized solid stored cold and dry is generally more stable than aqueous solutions.
Purity is method-dependent because different techniques detect different impurities. A peptide purity value from HPLC does not describe copper content or the amount of free peptide. Reports should specify the analytical method and the ratio of copper to peptide.
Inductively coupled plasma mass spectrometry or atomic absorption spectroscopy gives total copper after acid digestion. Combining that value with a peptide concentration from chromatography or amino acid analysis yields the metal-to-peptide ratio.