freeze-thaw raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2026-08-01. Anything still debated is marked as such rather than presented as settled.
Four amino acid substitutions separate the modified backbone from the parent GRF(1-29) sequence. These changes reduce recognition by dipeptidyl peptidase IV and related proteases, extending the interval before degradation. Development work in this area sought longer-acting GHRH analogs for endocrine investigation. Published descriptions treat the substitution set as a defining property of the core sequence, while the albumin-binding linker is described separately as an optional addition to that same backbone.
CJC-1295 is a synthetic peptide analog of growth hormone-releasing hormone, constructed on the 29-amino-acid fragment designated GRF(1-29). The name began as an internal development code during the 1990s and later spread through research supply catalogs and discussion forums. The molecule does not occur in nature; its sequence is engineered rather than isolated from tissue. Two related compounds are sold under this single label, and they differ by one appended chemical group that strongly influences how long the peptide remains in circulation.
The dividing feature between the two forms is a maleimide-based drug affinity complex, abbreviated DAC. In the DAC-bearing version, a linker attaches the peptide to serum albumin after administration, and that association slows removal from plasma. The version lacking DAC appears in catalogs as MOD GRF(1-29) or tetrasubstituted GRF(1-29). Because informal writing treats both as one item, comparisons drawn from such sources routinely blend measurements taken from two molecules with substantially different behavior.
Two forms circulate under the CJC-1295 name, and they differ by a single appended group. The version without a drug affinity complex carries four substitutions along the peptide chain, including a D-alanine near the amino terminus and replacements at three other positions. These changes block the enzyme dipeptidyl peptidase IV and remove a methionine residue that is prone to oxidation. The modified fragment is frequently labeled MOD GRF 1-29. Naming conventions are inconsistent across informal sources, which is a common source of confusion.
The second form adds a maleimide-bearing linker to the lysine at the carboxyl end. This group reacts with cysteine-34 on circulating serum albumin, forming a covalent bond that keeps the peptide in the bloodstream for far longer. ConjuChem developed the molecule as a way to extend the action of a peptide without frequent administration. The albumin attachment is the defining structural feature of the drug affinity complex version. Whether continuous exposure produces effects distinct from shorter pulses remains an unresolved research question.
| Property | Value | Notes |
|---|---|---|
| Molecular class | Synthetic peptide | Analog of growth hormone-releasing hormone |
| Chain length | 29 amino acids | Based on the GRF(1-29) fragment |
| Appearance | White to off-white lyophilized powder | Common research supply form |
| Solubility | Soluble in water and aqueous buffers | Powder requires reconstitution before use |
| Typical storage | −20 °C or below | Kept away from light and moisture |
The core sequence keeps the receptor-binding region of GHRH while replacing four positions that are vulnerable to dipeptidyl peptidase-4 and other proteases. Substitutions at positions 2, 8, 15, and 27 raise metabolic stability relative to the natural hormone. The N-terminal residues remain essential for activity, so changes there generally lower potency. Molecular weight sits near 3368 daltons for the tetrasubstituted analog without the linker, while the albumin-binding form is heavier because of the added maleimide group.
CJC-1295 is a synthetic peptide modeled on growth hormone-releasing hormone, the hypothalamic signal that prompts the pituitary to release growth hormone. Its sequence corresponds to the first twenty-nine residues of human GHRH, with four substitutions that slow enzymatic breakdown. Early descriptions placed the compound in research on growth hormone deficiency and related conditions, and later literature groups it with the long-acting GHRH analogs. The name appears in both laboratory and popular fitness writing, where it sometimes labels chemically different peptides.
Two related peptides circulate under the CJC-1295 label, and they differ mainly in how long they persist in circulation. The version carrying a drug affinity complex includes a maleimidopropionic acid linker that forms a covalent bond with serum albumin. The other version, usually written as modified GRF(1-29) or tetrasubstituted GRF(1-29), lacks that linker and is cleared quickly. Mixing the two produces inconsistent readings of published half-life values, because the linker rather than the receptor-facing sequence drives most of the difference.
Two related forms circulate in technical discussion under the same family name. The original version carries a drug affinity complex (DAC) that binds covalently to serum albumin after administration, and this linkage substantially extends circulation time. A second form, frequently written as modified GRF(1-29) or CJC-1295 without DAC, lacks that linker and clears much faster. The naming is a frequent source of confusion because the shorthand CJC-1295 can refer to either form depending on the source. Reports sometimes fail to specify which variant was studied.
The peptide backbone includes a D-alanine at position two, which resists cleavage by dipeptidyl peptidase IV, and several other substitutions that reduce degradation. Its molecular weight is roughly 3.4 kDa without the linker and about 3.6 kDa with it. The molecule is water soluble and is normally supplied as a lyophilized powder. Precise sequence and mass values depend on which variant is described, so technical documents usually state the exact form being referenced.
CJC-1295 is a synthetic peptide designed as a long-acting analogue of growth hormone-releasing hormone (GHRH). Its structure derives from the first 29 amino acids of native GHRH, a fragment often called GRF(1-29). Four substitutions were introduced to slow enzymatic breakdown and extend activity relative to the natural sequence. The compound was developed by ConjuChem as part of a broader effort to improve the pharmacokinetic profile of peptide hormones. It is studied in laboratory and clinical research settings rather than appearing as a naturally occurring substance.
Reconstitution is typically performed with sterile water or bacteriostatic water, added slowly against the vial wall. The resulting solution should be clear and colorless; cloudiness or visible particles suggest a problem with the material or the diluent. Once in solution, the peptide is less stable than the dry powder. Refrigerated storage at two to eight degrees Celsius is common for short-term holding, while freezing aliquots is described for longer periods.
Purity is most often assessed by reversed-phase high-performance liquid chromatography, reported as a percentage of total peak area. Identity is confirmed by mass spectrometry, which yields a molecular ion consistent with the expected sequence. Amino acid analysis and peptide mapping provide additional characterization. Reported purity values are method-dependent, so figures from different laboratories are not always directly comparable without details of column, gradient, and detection wavelength.
Reported half-lives differ widely between the two variants and between species. Values for the albumin-binding form are usually expressed in days, while the unconjugated form is measured in minutes to a few hours. Sampling schedules, assay sensitivity, and route of administration all influence the numbers, which limits direct comparison across studies. Whether sustained receptor occupancy produces different downstream effects from pulsatile stimulation remains an open question in the published work. Claims about relative potency should therefore be read alongside the specific study design that produced them.
Lyophilised powder is the usual supplied form. The material is hygroscopic, so vials are typically equilibrated to room temperature before opening in order to prevent condensation on the contents. Long-term storage is generally described at minus twenty degrees Celsius or colder, protected from light and moisture. Repeated freeze-thaw cycles are avoided because they promote aggregation and loss of soluble material. A reconstituted solution is considerably less stable than the dry powder and is normally kept refrigerated for short periods only.
=== Preparation of isotopes === Berkelium is produced by bombarding lighter actinides uranium (238U) or plutonium (239Pu) with neutrons in a nuclear reactor. In a more common case of uranium fuel, plutonium is produced first by neutron capture (the so-called (n,γ) reaction or neutron fusion) followed by beta-decay:
Based on MIC data and other studies, dalbavancin is more potent and bactericidal and therefore requires lower concentrations than vancomycin against these organisms. Dalbavancin also shows in vitro activity against vancomycin-susceptible Enterococcus faecium and Enterococcus faecalis. Other Gram-positive organisms belonging to the Bacillus spp., Listeria spp., and Corynebacterium spp. may show in vitro susceptibility, and dalbavancin may exhibit activity against enterococci expressing the VanB or VanC phenotype of acquired resistance against vancomycin. There is no clinically significant activity against Gram-negative bacteria.
The ilvGMEDA operon encodes the ilvGM (ALS II) pair as well as a branched-chain-amino-acid transaminase (ilvE), dihydroxy-acid dehydratase (ilvD), and threonine ammonia-lyase (ilvA). It is regulated by feedback inhibition in the form of transcriptional attenuation. That is, transcription is reduced in the presence of the pathway's end-products, the branched-chain amino acids. The ilvBNC operon encodes the ilvBN (ALS I) pair and a ketol-acid reductoisomerase (ilvC). It is similarly regulated, but is specific to isoleucine and leucine; valine does not affect it directly. Both the ilvGMEDA and ilvBNC operons are derepressed during shortages of the branched-chain amino acids by the same mechanism that represses them. Both of these operons as well as the third, ilvIH, are regulated by leucine-responsive protein (Lrp).
Cassinga must be revenged." It was from this communique that the name of the next major PLAN offensive was derived: Operation Revenge. After some deliberation, Huwala chose Katima Mulilo as his target and dispatched several PLAN reconnaissance teams to obtain data on firing positions and potential artillery observation posts. On 23 August 1978, PLAN bombarded Katima Mulilo with mortars and rocket fire, killing 10 SADF personnel. The next day, General Viljoen, General Geldenhuys and the Administrator-General of South West Africa flew out to Katima Mulilo to inspect the damage. All three narrowly escaped death when their SA.321 Super Frelon helicopter took ground fire from PLAN anti-aircraft positions at Sesheke. The SADF responded by bombarding Sesheke with its own artillery and making a sweep for PLAN insurgents up to a hundred kilometers north of the Cutline. On 6 March 1979, Prime Minister Botha ordered retaliatory strikes on selected targets in Angola and Zambia. The respective code names for the operations were Rekstok and Saffraan. Heliborne South African troops landed in the vicinity of four Angolan settlements: Heque, Mongua, Oncocua, Henhombe, and Muongo, which they canvassed for guerrillas. The SADF remained in Zambia for a significantly longer period, carrying out a series of uneventful combat patrols and ambushes for five weeks. While Operations Rekstok and Saffraan were unsuccessful in terms of tactical results, they did interrupt PLAN's attempts to rebuild its base camps near the border.
However, in 2015 a study building on earlier research found that happiness has no effect on mortality. "This "basic belief that if you're happier you're going to live longer. That's just not true." Consistent results are that "apart from good health, happy people were more likely to be older, not smoke, have fewer educational qualifications, do strenuous exercise, live with a partner, do religious or group activities and sleep for eight hours a night." Happiness does however seem to have a protective impact on immunity. The tendency to experience positive emotions was associated with greater resistance to colds and flu in interventional studies irrespective of other factors such as smoking, drinking, exercise, and sleep. Positive emotional states have a favorable effect on mortality and survival in both healthy and diseased populations. Even at the same level of smoking, drinking, exercise, and sleep, happier people seem to live longer. Interventional trials conducted to establish a cause-effect relationship indicate positive emotions to be associated with greater resistance to objectively verifiable colds and flu.
Sources: en.wikipedia.org
=== Feeding and excretion === Cnidarians feed in several ways: predation, absorbing dissolved organic chemicals, filtering food particles out of the water, obtaining nutrients from symbiotic algae within their cells, and parasitism. Most obtain the majority of their food from predation but some, including the corals Hetroxenia and Leptogorgia, depend almost completely on their endosymbionts and on absorbing dissolved nutrients. Cnidaria give their symbiotic algae carbon dioxide, some nutrients, and protection against predators. Predatory species use their cnidocytes to poison or entangle prey, and those with venomous nematocysts may start digestion by injecting digestive enzymes. The "smell" of fluids from wounded prey makes the tentacles fold inwards and wipe the prey off into the mouth. In medusae, the tentacles around the edge of the bell are often short and most of the prey capture is done by "oral arms", which are extensions of the edge of the mouth and are often frilled and sometimes branched to increase their surface area. These "oral arms" aid in cnidarians' ability to move prey towards their mouth once it has been poisoned and entangled. Medusae often trap prey or suspended food particles by swimming upwards, spreading their tentacles and oral arms and then sinking. In species for which suspended food particles are important, the tentacles and oral arms often have rows of cilia whose beating creates currents that flow towards the mouth, and some produce nets of mucus to trap particles. Their digestion is both intra and extracellular.
=== HLX === Following the release of Half-Life: Alyx in 2020, dataminers examining updates to the Source 2 engine discovered that Valve was developing a non-VR game codenamed HLX. On December 31, 2024, Mike Shapiro, the voice actor for the G-Man, posted a cryptic message on X suggesting "unexpected surprises" in the new year. In April, it was reported that HLX was being playtested and would be a sequel to Episode Two. Industry insiders, dataminers and leakers reported that Valve was planning a 2025 announcement for HLX. In December, the Insider Gaming senior editor Mike Straw said HLX was planned as a launch game for Valve's Steam Machine hardware, and the announcement had been delayed by the rising cost of RAM.
Earth The HIC of mantle rocks on Earth is highly variable; and that of mantle water is around −80‰ ~ −50‰ depending on its states such as fluid, hydrous phase, hydroxyl point defect, juvenile water (from degassing of the mantle), magmatic water (water equilibrated with a magma). Sun The Sun's DHR is around 21 ± 5 × 10−6. Mars The current HIC is enriched by a factor of 5 relative to Earth's seawater due to continual losses of H in Martian atmosphere. Therefore, the δD is estimated at around +4000‰. The DHRs of Jupiter and Saturn are nearly in the order of 10−5, and the DHRs of Uranus and Neptune are closer to 10−4. Hydrogen is the most abundant element in the universe. Variations in isotopic composition of extraterrestrial materials stem from planetary accretion or other planetary processes such as atmospheric escape, and are larger for H and N than for C and O. The preservation of D-enrichment is observed in chondritic meteorites, interplanetary dust particles and cometary Volatiles. From the helium isotope abundance data, the cosmic DHR is estimated at around 20 ppm: much lower than the terrestrial DHR of 150 ppm. The enrichment of D/H from the proto-solar reservoir occurs for most of the planets except for Jupiter and Saturn, the massive gaseous planets. The DHRs of the atmospheres of Venus and Mars are ~2 × 10−2 and ~8 × 10−4 respectively. The DHRs of Uranus and Neptune are larger than that of protosolar reservoir by a factor of ~3 due to their deuterium-rich icy cores.
Calvo Sotelo did not manage to stop the internal crisis of UCD ─ the "critical sector" led by Miguel Herrero y Rodríguez de Miñón and Oscar Alzaga approached Alianza Popular and the "social democratic sector" led by Francisco Fernández Ordóñez approached PSOE ─ which was aggravated by the defeat in the Galician elections of October 1981, in which the centrists were overtaken by Alianza Popular. Calvo Sotelo then tried to recompose the unity of the party by personally assuming the presidency of the party and reshuffling his government, in which the "strong man" became the vice-president Rodolfo Martín Villa, but at the beginning of 1982, the "flight" of deputies to Alianza Popular began. In May, UCD suffered a new setback in the Andalusian autonomic elections, in which the PSOE obtained the absolute majority and Alianza Popular again surpassed UCD in votes. Then Landelino Lavilla took over the presidency of the party but also failed to stop the "bleeding of splits". The Christian Democrats founded a new party, the Partido Demócrata Popular, and even Suárez left UCD to form his own, the Centro Democrático y Social. Faced with this situation, a broken and disbanded party, Calvo Sotelo dissolved the Cortes in August 1982 and called general elections.
Lucilia spp. (green-bottle fly) Cochliomyia spp. (screw-worm fly) Phormia spp. (black-bottle fly) Calliphora spp. (blue-bottle fly) Sarcophaga spp. (flesh fly or sarcophagids) Flesh flies, or sarcophagids, members of the family Sarcophagidae, can cause intestinal myiasis in humans if the females deposit larvae on meat or fruit.
Sources: en.wikipedia.org
Even though half-lives of hundreds or thousands of years would be relatively long for superheavy elements, they are far too short for any such nuclides to exist primordially on Earth. Additionally, instability of nuclei intermediate between primordial actinides (232Th, 235U, and 238U) and the island of stability may inhibit production of nuclei within the island in r-process nucleosynthesis. Various models suggest that spontaneous fission will be the dominant decay mode of nuclei with A > 280, and that neutron-induced or beta-delayed fission—respectively neutron capture and beta decay immediately followed by fission—will become the primary reaction channels. As a result, beta decay towards the island of stability may only occur within a very narrow path or may be entirely blocked by fission, thus precluding the synthesis of nuclides within the island. The non-observation of superheavy nuclides such as 292Hs and 298Fl in nature is thought to be a consequence of a low yield in the r-process resulting from this mechanism, as well as half-lives too short to allow measurable quantities to persist in nature. Various studies utilizing accelerator mass spectroscopy and crystal scintillators have reported upper limits of the natural abundance of such long-lived superheavy nuclei on the order of 10−14 relative to their stable homologs.
The independence of Poland had been campaigned for in Russia and in the West by Dmowski and in the West by Ignacy Jan Paderewski. Tsar Nicholas II of Russia, and then the leaders of the February Revolution and the October Revolution of 1917, installed governments who declared in turn their support for Polish independence.[d1] In 1917, France formed the Blue Army (placed under Józef Haller) that comprised about 70,000 Poles by the end of the war, including men captured from German and Austrian units and 20,000 volunteers from the United States. There was also a 30,000-men strong Polish anti-German army in Russia. Dmowski, operating from Paris as head of the Polish National Committee (KNP), became the spokesman for Polish nationalism in the Allied camp. On the initiative of Woodrow Wilson's Fourteen Points, Polish independence was officially endorsed by the Allies in June 1918.[c1] In all, about two million Poles served in the war, counting both sides, and about 400–450,000 died. Much of the fighting on the Eastern Front took place in Poland, and civilian casualties and devastation were high.
Since 1986, the restaurant has issued a calendar featuring Hooters Girls, with signings taking place in some of their restaurants. Since 1996, Hooters has held Miss Hooters International Swimsuit Pageant, a competition of Hooters Girls from around the world. The pageant once aired on Spike TV and is now livestreamed to Hooters restaurants and eventually posted on YouTube. An African-American woman won the Miss Hooters pageant for the first time in 2010: LeAngela Davis of Columbus, Ohio.
=== Pharmacodynamics === (+)-JRT is highly selective for a subset of serotonin receptors and does not bind to various dopamine, adrenergic, or histamine receptors, which is in contrast to LSD. It shows high affinity for the serotonin 5-HT2 receptors, with Ki values ranging from 2.0 to 184 nM. The drug is a potent partial agonist of the serotonin 5-HT2A and 5-HT2B receptors (EmaxTooltip maximal efficacy = 33–81% and 48–51%, respectively) and a full agonist of the serotonin 5-HT2C receptor (Emax = 89%). It is also an agonist of the serotonin 5-HT1A and 5-HT7 receptors, an antagonist of the serotonin 5-HT5A and 5-HT7 receptors, and a ligand of the serotonin 5-HT6 receptor. (+)-JRT does not have significant affinity for the serotonin 5-HT1B or 5-HT3 receptors, whereas its affinities for the other serotonin 5-HT1 receptors and the serotonin 5-HT4 receptor were not reported. The drug is 4.4- to 180-fold less potent than LSD as a serotonin 5-HT2A receptor agonist in vitro (EC50Tooltip half-maximal effective concentration = 0.4–90 nM vs. 0.09–0.5 nM, respectively) and is less efficacious than LSD in activating the receptor (Emax = 33% vs. 44–63%, respectively). It has been found to dissociate from the serotonin 5-HT2A receptor approximately 10-fold more quickly than LSD. (+)-JRT produces the head-twitch response (HTR), a behavioral proxy of psychedelic effects, in rodents, and hence would be expected to be hallucinogenic in humans. However, the drug shows a reduced HTR compared to LSD, producing less than half the maximal number of head twitches.
Sources: en.wikipedia.org
No. It is a laboratory-synthesized analog built on a fragment of the natural hormone. The natural peptide is shorter-lived and lacks the stabilizing substitutions found in the synthetic version.
DAC stands for drug affinity complex, a chemical group that binds the peptide to serum albumin. The binding slows clearance and lengthens the time the molecule stays in plasma compared with the unmodified analog.
Because two distinct molecules are discussed under one informal label. The albumin-binding version clears over several days, while the form without that group clears within roughly half an hour. Mixing results from both creates inconsistent figures.
Natural GHRH is degraded quickly by dipeptidyl peptidase-4 and related enzymes, giving it a half-life measured in minutes. CJC-1295 carries substitutions that slow that breakdown, so it stays intact longer. Both act at the same pituitary receptor and produce the same class of signal.