This is a working overview of electron paramagnetic resonance, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-06-29 and is reviewed periodically as new material appears.
Routine handling calls for minimizing freeze-thaw cycles and preparing solutions shortly before use. Glass or inert plastic containers reduce adsorption and metal leaching. Working stocks are often kept at 2–8 °C for short periods, while long-term reference material stays at −20 °C or below. Light protection is prudent because prolonged exposure may accelerate oxidation of the peptide. Documentation of lot number, concentration, and preparation date supports reproducibility in laboratory work.
Analytical verification typically combines reversed-phase high-performance liquid chromatography with ultraviolet-visible detection. The copper complex absorbs visible light near 600–630 nm, giving a characteristic blue signal. Mass spectrometry confirms molecular mass and can detect free peptide or mismatched copper stoichiometry. Copper content is often measured independently by inductively coupled plasma mass spectrometry or atomic absorption spectroscopy. Purity, counterion identity, and residual solvents are additional quality-control parameters that methods may address.
Solid GHK-Cu is generally stored as a dry powder under frozen conditions to limit degradation. The peptide bond can hydrolyze, and the copper center can be displaced by strong chelators such as EDTA. Aqueous solutions are less stable than the solid and may lose color or form precipitates over time. Temperature, pH, and oxygen exposure are the main variables that affect shelf life. Neutral to slightly acidic conditions tend to preserve the complex better than strongly alkaline media.
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.
| Property | Value | Notes |
|---|---|---|
| Physical state | Blue-violet solid | Typically supplied as lyophilized powder |
| Storage temperature | −20 °C or below | Desiccated, protected from light |
| Working stability | Hours to days at 2–8 °C | Depends on concentration and buffer |
| Identity test | RP-HPLC with UV-Vis | Visible absorbance near 600–630 nm |
| Copper assay | ICP-MS or AAS | Metal content confirms stoichiometry |
Several names circulate for the same material, which complicates literature searches. Cosmetic ingredient lists often use copper tripeptide-1, while older biochemistry papers use glycyl-L-histidyl-lysine or its abbreviation GHK. The copper complex is sometimes written as GHK-Cu(II) to make the oxidation state explicit. Terminology is not fully standardized, so matching a compound across sources requires attention to the exact sequence, the counterion, and the stated copper content. Reviews that compare studies must account for these naming differences before drawing conclusions.
GHK-Cu is the copper(II) complex of the tripeptide glycyl-L-histidyl-L-lysine, a short sequence of three amino acids. The peptide was first isolated from human plasma in 1973 during research on factors that influence tissue repair in liver. Its ability to bind copper ions became a central point of interest because the metal changes the peptide's chemistry and its behaviour in laboratory systems. Today the compound appears in cosmetic formulations, cell-culture studies, and biochemistry literature under several names.
The sequence carries three residues in the order glycine, histidine, lysine, which places a small, flexible chain around a single metal centre. Compared with larger copper-binding proteins, the complex is compact and its coordination chemistry can be reproduced with synthetic peptide in a laboratory. Published structural work agrees on the nitrogen donor set but differs in the exact geometry assigned under some conditions, so the arrangement is best treated as well characterised in outline rather than fixed in every detail.
GHK-Cu is a coordination complex formed between the tripeptide glycyl-L-histidyl-L-lysine and a copper(II) ion. The peptide was isolated from human plasma in the early 1970s by Loren Pickart, who observed that a plasma fraction from young donors stimulated growth in cultured liver cells. The copper-bound form is abbreviated GHK-Cu, while the metal-free peptide is written simply as GHK. In the research literature the complex also appears as copper tripeptide-1 and as glycyl-histidyl-lysine copper complex.
Copper(II) binds the peptide through four nitrogen donors: the terminal amino group, the imidazole nitrogen of histidine, and two deprotonated amide nitrogens of the peptide backbone. This tetradentate arrangement gives a roughly square-planar geometry, the thermodynamically favoured form near neutral pH. Because the amide nitrogens must lose a proton before they can coordinate, complex formation is strongly pH-dependent, and the fully coordinated species dominates only above mildly acidic conditions. Electronic transitions within the copper d orbital set produce the characteristic blue to violet colour in aqueous solution.
Identity and purity are usually assessed with reversed-phase high-performance liquid chromatography, often paired with mass spectrometry. Copper content is measured separately by techniques such as inductively coupled plasma mass spectrometry or atomic absorption. Amino acid analysis confirms the peptide sequence after hydrolysis. Because the metal and the peptide can be quantified independently, a complete certificate of analysis normally reports both values rather than a single purity figure. This separation of measurements is important when comparing suppliers.
Solid GHK-Cu appears as a blue to blue-violet powder, and the colour is a direct consequence of copper coordination. The complex dissolves readily in water and in many polar solvents, while the free peptide behaves differently. Solubility in nonpolar media is low, which limits its use in oil-based systems. Solutions are typically prepared fresh because the dissolved form is more exposed to hydrolysis and to loss of the metal ion than the dry powder. Working concentrations are usually low, and preparation notes often specify the solvent and the order of addition.
Dry material is typically held at low temperature, often around minus twenty degrees Celsius, and protected from moisture and light. Copper complexes can release their metal ion under acidic conditions or in the presence of competing chelators. Hydrolysis of the peptide backbone is a slower but real pathway, and the histidine residue is susceptible to oxidation over long periods. Stability statements therefore depend on formulation, pH, and container, and they should be read as conditional rather than absolute.
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.
Quality specifications for research material commonly state peptide purity, copper stoichiometry, counter-ion identity, and residual water content. Frequent counter-ions include acetate and trifluoroacetate, which differ in mass and in their effect on solubility and handling. Whether batch-to-batch differences in reported responses trace to these parameters or to assay conditions remains an open question, since published comparisons rarely control for all of them at once. Independent verification therefore normally pairs a purity measurement with an elemental copper measurement on the same lot.
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.
However, the Act's public register provision is facing legal challenges from local governments in the Cayman Islands and British Virgin Islands, who argue that it violates their Constitutional sovereignty. Under the Proceeds of Crime Act goods that criminals cannot legally account for are seized and sold at auction to raise funds. This is usually carried out by authorised auction houses and often within the geographical areas of the criminals.
Phosphopeptides are modified self antigens which may induce an immune response. Protein phosphorylation is a very important and frequent post-translational modification that can impact a protein's localization, stability, and whether or not it can dimerize or form stable bonds with other substances. It is vital to pinpoint which amino acid in the protein’s primary structure is being phosphorylated in order to understand the functions of a phosphopeptide. This is accomplished through phosphopeptide mapping, which involves digestion of a radioactively labeled protein, separation of phosphopeptide products, and finally analysis via high-performance liquid chromatography (HPLC) or mass spectrometry. Analysis of phosphopeptides can provide information about which amino acids are phosphorylated and how many sites on the primary sequence are phosphorylated. Phosphorylation of serine and threonine residues is conserved during MHC class I and MHC class II antigen processing. Phosphopeptides are thus displayed on the surface of cells. As modified self antigens, they are potentially immunogenic when compared to unmodified self proteins as the immune cells (T-cells) which recognise them are possibly not subject to central tolerance mechanisms. This may contribute to the potential capability of phosophopeptides to serve as tumor antigens in the treatment of colorectal cancer.
cloning The process of producing, either naturally or artificially, individual organisms or cells which are genetically identical to each other. Clones are the result of all forms of asexual reproduction, and cells that undergo mitosis produce daughter cells that are clones of the parent cell and of each other. Cloning may also refer to biotechnology methods which artificially create copies of organisms or cells, or, in molecular cloning, copies of DNA fragments or other molecules.
=== Africa === African socialism has been a major ideology around the continent and remains so in the present day. Although affiliated with the Socialist International, the African National Congress (ANC) in South Africa abandoned its socialist ideology after gaining power in 1994 and followed a neoliberal route. From 2005 until 2007, the country was wracked by thousands of protests from poor working-class communities. One of these gave rise to a mass democratic socialist movement of shack dwellers called Abahlali baseMjondolo which continues to work for popular people's planning and against the proliferation of capitalism in land and housing. In 2013, the National Union of Metalworkers of South Africa, the country's biggest trade union, voted to withdraw support from the AFC and the South African Communist Party and to form an independent socialist party to protect the interests of the working class, resulting in the creation of the United Front. Other democratic socialist parties in Africa include the Movement of Socialist Democrats, the Congress for the Republic, the Movement of Socialist Democrats and the Democratic Patriots' Unified Party in Tunisia, the Berber Socialism and Revolution Party in Algeria, the Congress of Democrats in Namibia, the National Progressive Unionist Party, the Socialist Party of Egypt, the Workers and Peasants Party, the Workers Democratic Party, the Revolutionary Socialists and the Socialist Popular Alliance Party in Egypt and the Socialist Democratic Vanguard Party in Morocco.
Nuclear medicine is concerned with studying human organ systems by administering radiolabelled substances (radiopharmaceuticals) to the body, which can then be imaged outside the body by a gamma camera or a PET scanner. Each radiopharmaceutical consists of two parts: a tracer that is specific for the function under study (e.g., neurotransmitter pathway, metabolic pathway, blood flow, or other), and a radionuclide (usually either a gamma-emitter or a positron emitter). There is a degree of overlap between nuclear medicine and radiology, as evidenced by the emergence of combined devices such as the PET/CT scanner. Pathology as a medical specialty is the branch of medicine that deals with the study of diseases and the morphologic, physiologic changes produced by them. As a diagnostic specialty, pathology can be considered the basis of modern scientific medical knowledge and plays a large role in evidence-based medicine. Many modern molecular tests such as flow cytometry, polymerase chain reaction (PCR), immunohistochemistry, cytogenetics, gene rearrangements studies, and fluorescent in situ hybridization (FISH) fall within the territory of pathology.
Sources: en.wikipedia.org
=== Phase 2 === Cannabidiol (CBD; ATL5; RLS103) – cannabinoid receptor modulator and other actions Cannabidiol (CBD; Empower CBD) – cannabinoid receptor modulator and other actions ENX-102 (ENX102) — α2, α3, and α5 subunit-containing GABAA receptor positive allosteric modulator and nonbenzodiazepine FKW00GA (FKW-00GA; TGW-00AA; TGW00AA) – serotonin 5-HT1A receptor partial agonist and serotonin 5-HT2A receptor antagonist JNJ-42165279 (JNJ-5279) – fatty acid amide hydrolase (FAAH) inhibitor (R)-Midomafetamine ((R)-MDMA; R-MDMA; EMP-01) – serotonin, norepinephrine, and dopamine releasing agent, weak serotonin 5-HT2A, 5-HT2B, 5-HT2C receptor agonist, entactogen, and weak psychedelic hallucinogen Non-racemic MDMA (ALA-002; 70–80% (R)-MDMA, 20–30% (S)-MDMA) – serotonin, norepinephrine, and dopamine releasing agent, weak serotonin 5-HT2A, 5-HT2B, 5-HT2C receptor agonist, entactogen, and weak psychedelic hallucinogen NTX-1472 (RO-6953958) – vasopressin V1A receptor antagonist ONO-1110 – endocannabinoid synthesis regulator and indirect cannabinoid receptor modulator [3] [4] [5] Oxytocin (intranasal potentiated oxytocin; TI-001; TI-114; TNX-1900; TNX-2900) – oxytocin receptor agonist Vilazodone (Viibryd) – serotonin 5-HT1A receptor partial agonist and serotonin reuptake inhibitor
Cell-Based Bone Tissue Engineering Clinical Tissue Engineering Center. State of Ohio Initiative for Tissue Engineering (National Center for Regenerative Medicine). Organ Printing. Archived 28 August 2008 at the Wayback Machine. Multi-site NSF-funded initiative. LOEX Center. Université Laval Initiative for Tissue Engineering.
The main difference between Minds and other extremely powerful artificial intelligences in fiction is that they are highly humanistic and benevolent. They are so both by design, and by their shared culture. They are often even rather eccentric. Yet, by and large, they show no wish to supplant or dominate their erstwhile creators. On the other hand, it can also be argued that to the Minds, the human-like members of the Culture amount to little more than pets, whose wants are followed on a Mind's whim. Within the Series, this dynamic is played on more than once. In 'Excession', it is also played on to put a Mind in its place – in the mythology, a Mind is not thought to be a god, still, but an artificial intelligence capable of surprise, and even fear.
== Bacterial cellulose-based textiles == Unlike plant-derived cellulose, bacterial cellulose offers superior mechanical properties, such as high tensile strength and flexibility, making it an attractive option for a wide range of textile applications. Moreover, the cultivation of bacterial cellulose can be achieved using simple fermentation processes, minimizing the environmental footprint associated with traditional textile manufacturing. Yeast, fungi and algae species including: the bacterium Pseudomonas fluorescens, the yeast Yarrowia lipolytica, the sponge Acanthella elongata, the algae Stoechospermum marginatum, and the fungus Candida albicans have all been researched for their ability to be used on substrates to create natural composites for biotextiles.
A raw egg is mixed with a bowl of Japanese rice. The rice can be cold, freshly cooked, or reheated. The egg may be broken directly into the rice bowl (either before or after the rice is added), or beaten in a separate bowl beforehand. Some people make a well in the mound of rice to pour the egg into. Variations on preparation include:
Sources: en.wikipedia.org
===== Interferon response pathway protects some cells from SeV infection ===== SeV can stimulate or inhibit the IFN-beta response pathway depending on the type of cell and host. If SeV triggers IFN production, the produced IFN further protects cells from next rounds of SeV infection. Multiple examples of IFN-beta protecting cells from SeV are described. Pretreatment of human lung fibroblasts MRC-5 cells with IFN-beta inhibits the replication of SeV. A similar IFN-beta protection against the virus has been observed for some human malignant cells that maintain the IFN response pathway. HeLa cells can be infected with SeV; however, incubation of these cells with IFN-beta causes inhibition of SeV replication. Multiple interferon stimulated genes (ISG) were identified as being required for this inhibition including IRF-9, TRIM69, NPIP, TDRD7, PNPT1 and so on. One of this genes TDRD7 was investigated in more detail. The functional TDRD7 protein inhibits the replication of SeV and other paramyxoviruses, suppressing autophagy, which is necessary for productive infection with these viruses. SeV also triggers the expression of IFN induced Ifit2 protein that is involved in protecting mice from SeV through as yet unknown mechanism. In addition, SeV triggers the expression of the chemokine interferon-γ inducible protein 10 kDa (CXCL10), which is involved in chemotaxis, induction of apoptosis, regulation of cell growth and mediation of angiostatic effects.
The modern practice of pathology is divided into a number of subdisciplines within the distinct but deeply interconnected aims of biological research and medical practice. Biomedical research into disease incorporates the work of a vast variety of life science specialists, whereas, in most parts of the world, to be licensed to practice pathology as a medical specialty, one has to complete medical school and secure a license to practice medicine. Structurally, the study of disease is divided into many different fields that study or diagnose markers for disease using methods and technologies particular to specific scales, organs, and tissue types.
The goal of protein design is to find a protein sequence that will fold to a target structure. A protein design algorithm must, thus, search all the conformations of each sequence, with respect to the target fold, and rank sequences according to the lowest-energy conformation of each one, as determined by the protein design energy function. Thus, a typical input to the protein design algorithm is the target fold, the sequence space, the structural flexibility, and the energy function, while the output is one or more sequences that are predicted to fold stably to the target structure. The number of candidate protein sequences, however, grows exponentially with the number of protein residues; for example, there are 20100 protein sequences of length 100. Furthermore, even if amino acid side-chain conformations are limited to a few rotamers (see Structural flexibility), this results in an exponential number of conformations for each sequence. Thus, in our 100 residue protein, and assuming that each amino acid has exactly 10 rotamers, a search algorithm that searches this space will have to search over 200100 protein conformations. The most common energy functions can be decomposed into pairwise terms between rotamers and amino acid types, which casts the problem as a combinatorial one, and powerful optimization algorithms can be used to solve it. In those cases, the total energy of each conformation belonging to each sequence can be formulated as a sum of individual and pairwise terms between residue positions.
Repair may be done by open surgery or by laparoscopic surgery. Open surgery has the benefit of possibly being done under local anesthesia rather than general anesthesia. Laparoscopic surgery generally has less pain following the procedure. In 2015, inguinal, femoral, and abdominal hernias affected about 18.5 million people. About 27% of males and 3% of females develop a groin hernia at some time in their life. Groin hernias occur most often before the age of one and after the age of fifty. Globally, inguinal, femoral, and abdominal hernias resulted in 60,000 deaths in 2015 and 55,000 in 1990.
Another perception of the vagina was that the release of vaginal fluids would cure or remedy a number of ailments; various methods were used over the centuries to release "female seed" (via vaginal lubrication or female ejaculation) as a treatment for suffocatio ex semine retento (suffocation of the womb, lit. 'suffocation from retained seed'), green sickness, and possibly for female hysteria. Reported methods for treatment included a midwife rubbing the walls of the vagina or insertion of the penis or penis-shaped objects into the vagina. Symptoms of the female hysteria diagnosis – a concept that is no longer recognized by medical authorities as a medical disorder – included faintness, nervousness, insomnia, fluid retention, heaviness in abdomen, muscle spasm, shortness of breath, irritability, loss of appetite for food or sex, and a propensity for causing trouble. It may be that women who were considered suffering from female hysteria condition would sometimes undergo "pelvic massage" – stimulation of the genitals by the doctor until the woman experienced "hysterical paroxysm" (i.e., orgasm). In this case, paroxysm was regarded as a medical treatment, and not a sexual release. The vagina has been given many vulgar names, three of which are pussy, twat, and cunt. Cunt is also used as a derogatory epithet referring to people of either sex. This usage is relatively recent, dating from the late nineteenth century.
Sources: en.wikipedia.org
Dry powder is typically stored frozen at −20 °C or lower, protected from moisture and light. Short-term working amounts may be kept refrigerated. Avoiding repeated temperature changes helps preserve the material.
Reversed-phase HPLC with UV-visible detection is common because the copper complex absorbs visible light. Mass spectrometry provides molecular mass confirmation. Copper-specific methods such as ICP-MS quantify the metal content.
The blue color comes from copper-ligand interactions. Displacement of copper by chelators or changes in pH can shift or diminish the color. Such changes often indicate that the complex has been altered.
Reverse-phase high-performance liquid chromatography with ultraviolet detection is the most common approach. Purity is expressed as a share of total peak area at a specified wavelength. Mass spectrometry is then used to confirm molecular identity.