A practical reference on Molecular weight distribution: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2025-10-31 and is reviewed periodically as new material appears.
The functional properties of collagen peptides depend on their molecular weight profile and amino acid sequence. They are highly soluble in water and produce low-viscosity solutions even at relatively high concentrations. Some peptides exhibit surface activity, which allows them to act as emulsifiers or foaming agents in food systems. The absence of a rigid triple-helical structure distinguishes them from gelatin, which can form gels upon cooling. Chromatographic separation and mass analysis are used to characterize the peptide mixture.
Collagen peptides are short chains of amino acids derived from collagen, a structural protein found in connective tissues such as skin, bone, and cartilage. The production process involves breaking native collagen into smaller fragments through hydrolysis, which cleaves peptide bonds. Unlike intact collagen, these peptides dissolve in water and do not form a triple helix. Commercial preparations typically contain peptides with molecular weights ranging from about 2,000 to 20,000 daltons. The term collagen peptide is often used interchangeably with hydrolyzed collagen or collagen hydrolysate.
One challenge in collagen peptide analysis is the absence of a single reference standard that covers all possible molecular weight fractions. Products from different sources or hydrolysis conditions yield different peptide profiles, complicating direct comparisons. Some laboratories use gelatin or a defined peptide mixture as a calibration standard, but this approach has limitations. Additionally, the term "collagen peptide" itself lacks a universally accepted molecular weight cutoff. Ongoing discussions aim to establish more consistent definitions and testing protocols for regulatory and research purposes.
Quality control of collagen peptides relies on methods that characterize molecular weight distribution, amino acid composition, and purity. Size exclusion chromatography (SEC) is commonly used to estimate the molecular weight profile of peptide mixtures. High-performance liquid chromatography (HPLC) can separate and quantify individual peptide fractions. Mass spectrometry provides detailed information on peptide sequences and modifications. These techniques help verify that a product meets declared specifications, though standardization across laboratories remains limited.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Typical for spray-dried commercial preparations |
| Solubility | Water-soluble | Dissolves in cold water; no gel formation |
| Average molecular weight | 2,000–20,000 Da | Varies by hydrolysis time and enzyme |
| Typical storage | Cool, dry, sealed container | Protect from moisture and heat |
| Common synonyms | Hydrolyzed collagen, collagen hydrolysate | Used interchangeably in literature |
Production begins with cleaning and mincing raw collagen-rich tissues. The material undergoes pretreatment to remove non-collagenous components, followed by hydrolysis using enzymes such as pepsin or alcalase, or by acid or alkaline treatment. Reaction time, temperature, and pH influence the average molecular weight of the resulting peptides. After hydrolysis, the mixture is filtered, concentrated, and dried, often by spray drying. The final product is a powder with a characteristic amino acid profile rich in glycine, proline, and hydroxyproline.
Collagen peptides are distinguished from gelatin by their lower average molecular weight and better solubility in cold water. Gelatin forms gels upon cooling, while collagen peptides typically do not. Molecular weight distributions for commercial collagen peptides often range from about 2 to 20 kilodaltons, though exact profiles vary by manufacturer and process. Products may be sold as powders, capsules, or liquids. The term "collagen hydrolysate" is frequently used as a synonym, although labeling conventions differ across regions.
Collagen is a structural protein found in connective tissues of animals, and collagen peptides are short amino acid chains produced by hydrolyzing native collagen into smaller fragments. The hydrolysis process typically uses enzymes or acids under controlled conditions. Commercial collagen peptides often come from bovine hide, porcine skin, or fish scales. The resulting material is water-soluble and differs from intact collagen in molecular size and behavior. The term 'collagen peptide' generally refers to a mixture of peptide chains rather than a single defined molecule.
Storage and handling of collagen peptides require protection from moisture, heat, and light. The powders are hygroscopic and can absorb water from the air, leading to clumping or microbial growth. Typical storage conditions are a cool, dry place at room temperature or below, in tightly sealed containers. Some manufacturers recommend refrigeration for long-term stability. Solutions prepared from the powder are less stable and should be used promptly or preserved according to validated protocols.
Production of collagen peptides begins with raw materials such as bovine hide, porcine skin, fish scales, or poultry cartilage. The collagen is extracted, often with acid or alkaline treatment, and then subjected to hydrolysis using enzymes like pepsin or alcalase, or chemical agents. Enzymatic hydrolysis is favored for its mild conditions and controllability. The resulting mixture is filtered, concentrated, and dried to yield a powder. Process parameters such as temperature, pH, and enzyme-to-substrate ratio determine the molecular weight profile and yield.
Amino acid composition of collagen peptides reflects that of the parent collagen, with glycine, proline, and hydroxyproline being particularly abundant. Glycine appears at nearly every third residue in the repeating sequence Gly-X-Y, where X and Y are often proline or hydroxyproline. This pattern is partly retained in short peptides, though hydrolysis can cleave at various sites. Hydroxyproline is uncommon in most other proteins and serves as a marker for collagen-derived material. The presence of these amino acids contributes to the unique properties of collagen peptides, including their resistance to certain proteases.
Molecular weight distribution is a key characteristic of collagen peptide preparations and influences solubility, viscosity, and absorption behavior. Low-molecular-weight fractions, often below 3,000 daltons, dissolve readily and may pass through intestinal barriers more efficiently than larger fragments. Higher-molecular-weight fractions can form viscous solutions and may retain some gel-like properties. Analytical techniques such as size exclusion chromatography reveal a broad distribution rather than a single peak. The average molecular weight is frequently reported, but the range and proportions of different sizes vary by manufacturer and process.
Manufacturing collagen peptides begins with collagen-rich raw materials such as bovine hide, porcine skin, fish scales, or poultry cartilage, which undergo washing, size reduction, and pretreatment to remove non-collagen proteins and fats. Extraction may use acid, alkali, or heat. Hydrolysis then breaks the collagen into smaller peptides, often with enzymes such as pepsin, papain, or alcalase. Process conditions of time, temperature, pH, and enzyme dose determine the final molecular weight distribution. After hydrolysis, the solution is filtered, concentrated, and dried into powder.
Quality testing of collagen peptides relies on several analytical methods. Molecular weight distribution is commonly measured by size-exclusion chromatography, sometimes paired with multi-angle light scattering. Amino acid composition is determined by ion-exchange chromatography or reversed-phase high-performance liquid chromatography after acid hydrolysis, while protein content is estimated by Kjeldahl or Dumas nitrogen analysis. Moisture, ash, and heavy metals are checked against specification limits. These tests help ensure consistency and detect adulteration with other proteins.
=== 1988 === 11 February Running to Time, about the new InterCity 225; the National Express Coaches Rapide service; the project team of the Intercity 225, with project director Mike Rollin, and Mike Newman of GEC; the 225 train had to be delivered on 14 February 1988, with an operational life of thirty years; the InterCity 125 was not intended to have been primarily developed - in a board meeting, the commercial directors were not technologically knowledgeable of trains, and asked about alternatives, to be told by an engineering director that a 125 mph diesel train could be developed in two years, so the HST began at that meeting; the British Rail APT-E prototype, powered by the Leyland 2S/350 gas turbine; in 1974 BR commissioned the APT-P, which had ten years of development, due to the active tilting suspension; the 225 train was possibly to enter service on the UK's only large electrified line, the West Coast Main Line, but the much-straighter and faster East Coast Main Line was being electrified, so BR decided to implement the 225 train on the ECML instead; Crewe railway station, which opened in 1837, and where trains were first built nearby in 1843; Steve Corfield, of Crewe Works; the unsprung mass of a train, and Cardan shafts; Roger Ford of Modern Railways; John Prideaux, director of InterCity; David Carter of DCA in Warwick, who designed the livery; the Modernisation Plan was published in December 1954, which had advocated the electrification of the ECML, and the phasing-out of steam travel; the late-1980s ECML electrification had cost BR £350m - it was not government-funded, with 2,800 miles of copper wire, and 33,000 support masts, overseen by Don Heath; all of the improvements in the UK were on old lines of track, but France and Germany had built entire new electrified lines - the TGV was planned from the mid-1960s; G. Freeman Allen of Jane's World Railways; the 225 train underframe being built at Crewe Works; GEC Traction at Preston, Lancashire, Al Reed, the separately excited (Armature Controlled DC Motor) brushed DC electric motor, and Gerald West; the right-angle gearboxes were built by David Brown Ltd and Voith of Heidenheim an der Brenz in southern Germany; Eric Black of Metro-Cammell in Washwood Heath; the ST41 bogies were made by SIG Combibloc Group of Neuhausen am Rheinfall in Switzerland. Narrated by Robin Ellis, produced by Patrick Uden, directed by Paul Fabricius, made by Uden Associates. 12 February Playing with Fire 17 July The Air Fix!, about aviation safety; a television adaptation of a black comedy theatre production by 35-year-old James Castle, dressed as an airline pilot, largely featuring Turkish Airlines Flight 981, the Ermenonville air disaster, in France on 3 March 1974, to this day the worst airliner crash, without any survivors, with 177 British people killed, when a cargo door ruptured, and the subsequent enquiry led to a cover up by the airline and aviation authority; the DC10 had known design failings in its fuselage, and its cargo door design was known to be faulty by the aircraft manufacturer; the American Airlines Flight 96 crash had happened on 12 June 1972, involving a design failure of the cargo door, but the FAA nonetheless gave the DC-10 a certificate of airworthiness; the DC10 had been rushed into service; James Castle accused the aircraft industry of callous negligence; James Castle had been a British Airways aircraft maintenance technician from 1969 to 1977 at Heathrow Airport; he listed the numbers of children that lost one or both parents in the crash, and the numbers of women who were widowed; the theatre production had been going since December 1986, directed by Caroline Noh Narrated by James Castle, produced by Ben Gooder, made by Uden Associates 24 July Nic's Boat, about Nic Bailey, a 37-year-old architect with Foster and Partners; he designed a 40-ft trimaran, called MTC, for the Carlsberg Single-Handed Trans-Atlantic Race on 5 June 1988; he had helped to design the 1978 Sainsbury Centre for Visual Arts in Norwich and the Renault Centre in Swindon; boat builder Spud Rowsell in Exmouth, with Phil Morrison; the hull cost £46,000, and the rigging cost £46,000; the mast and rigging were fitted at Topsham, Devon; Robin Knox-Johnston; French yacht designer Bruno Fehrenbach; he sailed the Atlantic between the Rhumb Line Route and the Great Circle Route; some yachts made the journey to Newport, Rhode Island in ten days; the yacht mast was constructed by Proctor South West. Produced by Michael Wills, directed by Bob Bee, made by Juniper Productions 31 July The Living Dead 7 August Zen and the Art of TV Manufacture, a Panasonic TV factory in South Wales; in 1933 the company founder Kōnosuke Matsushita established seven guiding commercial principles; the Fidelity TV factory in west London was given one year - 1988 - to turn its fortunes around or be closed; the factory's closure was announced to the workforce on 25 January 1988, with the site closing at the end of July 1988; Amstrad bought the Fidelity name in May 1988. Narrated by Alan Howard, directed by Patrick Uden, produced by Michael Proudfoot, made by Uden Associates 14 August How Good Is Soviet Science?, about the political inhibition of Soviet technology in the 1980s; in many ways the Soviet Union in 1987 was a backward and underdeveloped nation, with food queues; the Soviet system didn't respond to changes in demand - everything was planned years in advance; physicist Alexander Prokhorov, who won the Nobel Prize for Physics in 1964; Russians were proud of mathematicians Pafnuty Chebyshev and Nikolai Lobachevsky; large government centrally planned projects were compatible with the communist system, notably its space programme; by the 1970s, the Russians realised that they were some distance behind other countries, such as in disciplines of computing and genetics; science teaching was emphasised at Soviet schools, and English was well taught as well; after secondary schools, half went into science; theoretical science was where Soviet teaching excelled, such as at the Steklov Institute of Mathematics; Yuri Ovchinnikov wanted to improve Soviet science; in the early 1950s, the Soviet Union tried to ignore the findings of genetics, through the work of Trofim Lysenko, who claimed that genetics was anti-communist, known as Lysenkoism leading to many scientists being imprisoned and executed; in the 1960s, a set of large biological research centres were built at Pushchino; one of the most well-built research institutes was the Shemyakin Institute of Bioorganic Chemistry, for biotechnology; Stalin did not like computer science, and it was largely banned until 1958; the Soviets were always years behind in computer science; the first recognisable transistor Soviet computer was the BESM-6 in the 1960s; later computers were the ES EVM series, copied from the IBM System/360; the Akademgorodok (Academic City) in Novosibirsk; the Institute of Automation and Electrometry researched optical memory on holographic slides to and much work on lasers; collaboration between Soviet research and Soviet industry was long-winded, maybe almost impossible - the centrally planned Soviet industry could not sufficiently adapt for short-term changes, as it had to be monotonously planned years in advance, for mass production; Soviet government research was perhaps excellent nonetheless; not many Soviet scientists could travel to international conferences; dissemination of current worldwide science was limited throughout the Soviet Union, due to widespread government restrictions; Suite No. 2 in B minor, BWV 1067. Narrated by US technology historian Loren Graham, produced by Chris Durlacher, directed by Martin Smith, made by Uden Associates, NDR and WGBH. Shown on Nova on 17 November 1987 and 22 March 1988 21 August Toys for the Boys, about the Williams racing team; Graham Hill and Jim Clark in 1967; Tomorrow's World in 1967, narrated by Derek Cooper; journalist Peter Windsor of Williams; aerodynamicist Frank Dernie, head of research at Williams; Keith Botsford, motor racing editor of the Sunday Times; the German racing manager Alfred Neubauer, in the late 1930s; there were 18 F1 teams, with 7 being British; Mobil Oil paid Williams £2.5m for advertising on the cars of Nigel Mansell and Riccardo Patrese; the Williams FW11; racing driver Howden Ganley; part of a BBC Horizon documentary broadcast on 9 March 1981, featuring the Williams FW07, and likewise narrated by Martin Jarvis and produced by Patrick Uden; engineering director Sir Patrick Head; Bach Mass in B minor; Mike Hawthorn, was killed on a public road, the A3 Guildford bypass, in his Jaguar Mark 1 on 22 January 1959; Canadian Gilles Villeneuve was thrown from his Ferrari, when qualifying for the 1982 Belgian Grand Prix; Swedish Ronnie Peterson, died after an accident on the start line at the 1978 Italian Grand Prix; Italian Elio de Angelis was killed in May 1986 at the Circuit Paul Ricard in south-east France; British Piers Courage burned to death at the 1970 Dutch Grand Prix; Jim Clark hit a tree on 7 April 1968 at the 1968 Deutschland Trophäe in the north-west of Baden-Württemberg; German Jochen Rindt was killed at the 1970 Italian Grand Prix after winning the championship in the same year, which was awarded posthumously; Bach Mass in B minor; Frank Williams had a crash on 8 March 1986 in the south of France, with Peter Windsor, in a Ford Sierra, making him quadraplegic; the Williams wind tunnel; Alan Jones waving the British flag at the 1980 Grand Prix; the 1988 season Williams car had a Judd V8 engine; the closing fanfare of Les préludes by Liszt; the documentary ends with German military march Prussia's Glory. Narrated by Martin Jarvis, produced by Patrick Uden, made by Uden Associates 28 August Cold Spring, Morning Sun, about atomic physicist Joan Hinton and her husband Erwin Engst. Joan's mother was teacher Carmelita Hinton. Joan worked on the top secret Manhattan Project at Los Alamos in 1944 which produced the atomic bombs that were dropped on Hiroshima and Hagasaki in the summer of 1945. After the war, Joan, her brother Bill, and her husband Erwin (Sid) Engst travelled to China to join Mao Ze Dong and the cultural revolution. Over the next five decades, Joan and Sid became pioneers in Chinese agricultural science and technology. Narrated by Liza Goddard, written, produced and directed by Chris Haws, Made by InCA. 18 September Taking the Tunnel, who would be travelling through the Channel Tunnel; the tunnel would open in May 1993; Colin Kirkland, technical director of Eurotunnel; Roger Vickerman of the University of Kent; historian Corelli Barnett, and how France and Germany spent money after the war improving rail infrastructure; journalist Kathy Watson; a working model was built of the two Channel rail terminals; 90% of the tunnel went through chalk; the French end was built much more water-tight than the English end, due to the worse geology; the tunnel was around one mile long at the English end, to meet the French side in 1990; the Single Market would stop duty free sales on the Channel ferries; the former Night Ferry across the Channel, which operated until 30 October 1980; TGV Est would connect Bordeaux, and TGV Nord would connect to Germany, the Netherlands, with a spur to the new tunnel; Richard D. North; tolls on the autoroutes discouraged local traffic, which slowed down British motorways; Daniel Ghouzi of Transmanche; Martin Simmons of Kent County Council; A292 junction of M20; Corelli Barnett believed that the British civil service was best at fudging, whereas the French civil service had been trained differently at the French grandes ecoles; a VTG ship from Dover to Dieppe carried trains; freight journeys over 250 miles were most cost effective by rail, but did lack logistical flexibility at either end; Michael Barclay of Tiphook Rail; a distribution centre in Paddock Wood in Kent, built by the Spanish Transfesa; UIC gauge was the main European gauge for freight; Artura Boix of Transfesa; Richard Hope of Railway Gazette; British trains had a 25 tonne axle weight, more than the European 22 tonnes; early plans for the new Eurostar trains, which would be dual voltage for travelling in England and France; rail writer Geoffrey Freeman Allen; the French trains would leave from the Gard du Nord; customs checks would be at the British end in London, but not in France; British Rail planned a high speed line across Kent to open in 1998 from King's Cross, but it would not open until September 2003, and to London in November 2007; Roger Ford of Modern Railways. Narrated by Geoffrey Palmer, produced by Patrick Uden, directed by Paul Fabricius, made by Uden Associates 25 September Road Test about road transport in the UK; there were two million vehicles in the UK in 1930; a test drive would be conducted from The Point, Milton Keynes at 8.30am to Maidstone, by different routes - Mike McDonald of the University of Southampton and Margaret Bell of the University of Nottingham in a Volvo 850 would go across London, and Peter Bonsall and Howard Kirby of the University of Leeds in a Volkswagen Passat B3, would follow the M25 to the north of London, George Hazel of Napier College and John Wootten in a Ford Granada would follow the M25 south of London, and Martin J. H. Mogridge would take the train on the new Thameslink from Bedford railway station via Blackfriars Railway Bridge; the test would be directed from the Road Traffic Research Centre at Middlesex Polytechnic, with Chris Wright, Peter Hills from Newcastle University, and psychologist Ivan Brown from the Applied Psychology Unit (MRC Cognition and Brain Sciences Unit) in Cambridge; variable-message signs (VMS) on the M6; before joining the M25, the vehicles had an average speed of 50 mph; the early plans in the 1940s for the M25, which the M25 to the south and west of London, now largely follows; when the M25 needed to be built, in the 1960s, many environmental objections had arisen for it to be built; Russ Kane in Capital Radio's Flying Eye; David Marsh at the AA Roadwatch studio in north London; the ramp meter, installed on the M6 by John Wootten; all of London's traffic lights were controlled from a computer centre in Westminster, with software (Split Cycle Offset Optimisation Technique) developed by Dennis Robertson; the Volvo 850 enters London along the Edgware Road and Park Lane to Hyde Park Corner; the prototype Autoguide system invented by Ian Catling; automatic vehicle identification (AVI) and piezoelectric strips developed at the University of Nottingham Department of Civil Engineering, and tested by Peter Davies on the Nottingham ring road, next to the QMC; the Volkswagen Passat arrives first at the Great Danes Hotel, making the 107 miles in two hours seventeen minutes, an average speed of 47 mph; the route south of London - 119 miles, also has a 47 mph average speed; the 96-mile rail journey had an average speed of 35 mph; the programme content would be copied by Top Gear fifteen years later. Narrated by Martin Jarvis, produced by David Sharp, directed by Mike Tomlinson, made by Orlando Productions 9 October Look, No Hands! about technology outpacing human knowledge; Hubert Dreyfus of University of California, Berkeley; Martin Corbett, industrial psychologist at the University of Warwick; work by Mike Cooley, and systems design; mechanical engineer Frederick Winslow Taylor and his meticulous improvements to industrial methods, in his book The Principles of Scientific Management; John Harris, manager of the Rolls-Royce helicopter engine plant at Leavesden, Hertfordshire; perhaps automation in engineering manufacturing processes could perhaps add or enhance, rather than totally replace, which required and produced less directly competent workers. Produced by Debra Hauer, directed by Christopher Rawlence, made by Hauer Rawlence Productions 16 October Spytech, John Pike of the Federation of American Scientists and how the Space Shuttle was built mostly for low Earth orbit reconnaissance satellites; but the Titan 34D was also available for many spy satellite launches; Christopher Andrew of the University of Cambridge; Harry Rositzke of the CIA, and the disastrous Operation Red Sox, from 1949 to 1953; William Colby, Director from 1973 to 1976 of the CIA, and how spying methods that worked in Germany during World War II were simply hopeless in a possibly more bizarre culture of communist eastern Europe in the early 1950s, so Ferret missions by B-29 aircraft over the border were attempted instead, but many were shot down; the Americans decided to go for high-altitude reconnaissance; on 1 May 1960, an aircraft photographing a missile construction factory, pilot was sentenced to 10 years, but released after two years in exchange for Rudolf Abel; H. Keith Melton and notorious improvised technology of the KGB; the Russian defector Stanislav Levchenko; the burst transmission method; camera lenses for spy satellites made by Itek; the Space Shuttle was built to maintain and repair the Key Hole set of spy satellites, such as KH-11 KENNEN, launched by the National Reconnaissance Office (NRO) in 1976, and introduced digital photography, and EOSAT and its Landsat program; Jeffrey T. Richelson, a writer on national security; Major-General George Keegan of the Twenty-Fifth Air Force described how the Soviet Union got to know when spy satellites would be overhead, and would hide anything sensitive; listening satellites sent their data to the NSA at Fort Meade in Maryland, such as data from Magnum, launched by the secret STS-51-C mission in January 1985; Paul Bracken and all-source intelligence fusion; Soviet intelligence in the US was quite widespread, with up to 800 spies operating out of Soviet trade missions, and operated much more widespread than the US had attempted; the new KH-12 satellite, that launched in November 1992, could see through clouds. Narrated by Mike Short, produced by Claudia Milne, made by Twenty Twenty 23 October Bamboo, the importance of bamboo to the Chinese economy; Prof Hsiung Wenyue of the Bamboo Research Centre of Nanjing Forestry University; bamboo structures do not collapse in high winds; over a thousand species of bamboo; bamboo dies out for ten years, then grows again; only 15% of China can be cultivated; bamboo can grow four feet in 24 hours, it is the fastest growing plant; bamboo has a tensile strength twice as much as timber; hospitals in China worked with herbal remedies; bamboo traders had quotas set by the Chinese government; bamboo shoots were mostly exported to Japan; growing bamboo helped soil structure; the Chinese government encouraged the growing of bamboo, as an alternative to timber. Narrated by Jenny Agutter, produced by Michael Blakstad, directed by Patrick Fleming, made by Workhouse Productions, made in cooperation with China Central Television 30 October Heavy Metal, chemist Neil Ward of the University of Surrey, who found abnormal pregnancies; medical doctor Robin Russell-Jones of the Campaign for Lead Free Air; environmental chemist Brian Davies of the University of Bradford; footage from the 1971 BBC A Public Poison, with chemist Derek Bryce-Smith, and Patrick Lawther of St Bartholomew's Hospital; Gloria all'Egitto from Aida by Giuseppe Verdi, with the assembly line of the Rover 800; Robin Brundle; Eric Fountain of Vauxhall Motors; Ojos Criollos by Louis Moreau Gottschalk. Narrated by Catherine Robins, produced by Michael Blakstad, made by Workhouse Productions 13 November Free Flight, about gliding, with Derek Piggott in a Rolladen-Schneider LS4 at Booker Gliding Centre in Buckinghamshire; in the UK there were about 350,000 flights and 2 deaths each year; a Schleicher ASW 24 in a wind tunnel with Loek Boermans at TU Delft Faculty of Aerospace Engineering in the Netherlands; the Schleicher ASH 25 with glider pilot John Jeffries at London Gliding Club west of Dunstable; at Wasserkuppe, a 3,000 ft mountain in the east of Hesse in the centre of Germany is where gliding mostly developed in the 1920s by the Deutsche Forschungsanstalt für Segelflug, due to German powered-aircraft manufacturing being legally restricted; nearby at Poppenhausen, Hesse is Alexander Schleicher GmbH & Co, with designer Gerhard Waibel, where gliders had wings made from carbon fibre, and covered in kevlar for torsional stiffness; the first glider of a contemporary design was the Akaflieg Stuttgart fs24 in 1951. Narrated by Robert Gary 20 November Chaos, Tim Palmer of the ECMWF; mathematician Robert L. Devaney; German mathematician Heinz-Otto Peitgen and fractal geometry; strange attractors in dynamical systems, such as weather systems; David Rand of the University of Warwick, and period-doubling bifurcation, discovered in 1975 by mathematician Mitchell Feigenbaum discovered; fractal landscapes; British mathematician Michael Barnsley, and affine transformations, which are applied to digital image processing; the chaos game; Soviet physicist Lev Landau; physicist Harry Swinney of the University of Texas; economist James B. Ramsey; Ian Stewart of the University of Warwick, and the unpredictable rotation of Hyperion. Written, produced and directed by Chris Haws, the programme was made by Independent Communications Associates (InCA). In 1989, it won the SciTech Award for best scientific documentary. 27 November The Art of Deception, about camouflage, deception, decoys and stealth. The Northrop Grumman B-2 Spirit was first displayed on Tuesday 22 November 1988, just five days before the programme was aired. Featured interviewees include: Richard P. Hallion of Wright-Patterson Air Force Base; Peter Varnish of the Admiralty Research Establishment at Funtington in West Sussex; defence writer Antony Preston; Roy Behrens of the Art Academy of Cincinnati; Lt Col Chris Nash of Surveillance, Target Acquisition, Night Observation and Counter-surveillance (STANOC); Major William Marshak of the AAMRL - now the 711th Human Performance Wing; Captain Brian Perowne, commanding officer of HMS Brazen (F91); aviation writer Bill Sweetman, and Commander Patrick Walker, commanding officer of HMS Trafalgar (S107) a Royal Navy hunter-killer submarine; John Hall of the Admiralty Research Establishment (former Admiralty Experiment Works) at Haslar. Narrated by Nick Chilvers, Written, produced and directed by Chris Haws, made by InCA and WGBH Boston
== Mechanism == Neuropeptides are released by dense core vesicles after depolarization of the cell. Compared to classical neurotransmitter signaling, neuropeptide signaling is more sensitive. Neuropeptide receptor affinity is in the nanomolar to micromolar range while neurotransmitter affinity is in the micromolar to millimolar range. Additionally, dense core vesicles contain a small amount of neuropeptide (3 - 10mM) compared to synaptic vesicles containing neurotransmitters (e.g. 100mM for acetylcholine). Evidence shows that neuropeptides are released after high-frequency firing or bursts, distinguishing dense core vesicle from synaptic vesicle release. Neuropeptides utilize volume transmission and are not reuptaken quickly, allowing diffusion across broad areas (nm to mm) to reach targets. Almost all neuropeptides bind to G protein-coupled receptors (GPCRs), inducing second messenger cascades to modulate neural activity on long time-scales. Expression of neuropeptides in the nervous system is diverse. Neuropeptides are often co-released with other neuropeptides and neurotransmitters, yielding a diversity of effects depending on the combination of release. For example, vasoactive intestinal peptide is typically co-released with acetylcholine. Neuropeptide release can also be specific. In Drosophila larvae, for example, eclosion hormone is expressed in just two neurons.
=== United Kingdom === In the United Kingdom, following a local newspaper story in October 2005, a parliamentary Early Day Motion was raised calling for Salvia divinorum to be banned there. However, it only received 11 signatures. A second motion raised in October 2008 attracted 18 signatures, and it was reported that Mann had also written to Jacqui Smith, then Home Secretary. The Advisory Council on the Misuse of Drugs, the independent body that advises UK government on drugs, was asked to investigate further. On the 28 January 2016, the Psychoactive Substances Act 2016 was passed. The act came into force on 26 May 2016, across the entire United Kingdom, making S. divinorum illegal to possess with intent to supply, possess on custodial premises, import for human consumption, or produce for human consumption. The two sponsors for the bill were Conservative House of Lords member Michael Bates and Conservative MP Theresa May.
== Further reading == Armstrong PW, Pieske B, Anstrom KJ, Ezekowitz J, Hernandez AF, Butler J, et al. (May 2020). "Vericiguat in Patients with Heart Failure and Reduced Ejection Fraction". N Engl J Med. 382 (20): 1883–1893. doi:10.1056/NEJMoa1915928. hdl:11370/94a25118-d24e-4efa-94a0-3b46279b519c. PMID 32222134.
=== Government expenditure === Parallel to the high tax level, government expenditure makes up a large part of GDP, and the government sector carries out many different tasks. By September 2018, 831,000 people worked in the general government sector, corresponding to 29.9% of all employees. In 2017, total government expenditure amounted to 50.9% of GDP. Government consumption took up precisely 25% of GDP (e.g. education and health care expenditure), and government investment (infrastructure etc.) expenditure another 3.4% of GDP. Personal income transfers (for e.g. elderly or unemployed people) amounted to 16.8% of GDP. Denmark has an unemployment insurance system called the A-kasse (arbejdsløshedskasse). This system requires a paying membership of a state-recognized unemployment fund. Most of these funds are managed by trade unions, and part of their expenses are financed through the tax system. Members of an A-kasse are not obliged to be members of a trade union. Not every Danish citizen or employee qualifies for a membership of an unemployment fund, and membership benefits will be terminated after 2 years of unemployment. A person that is not a member of an A-kasse cannot receive unemployment benefits. Unemployment funds do not pay benefits to sick members, who will be transferred to a municipal social support system instead. Denmark has a countrywide, but municipally administered social support system against poverty, securing that qualified citizens have a minimum living income.
Sources: en.wikipedia.org
Casuarinas are flowering plants with fruit and leaves resembling the leaves and cones of the gymnosperm pines Some dicots (Anemone) and monocots (Trillium) in inhospitable environments are able to form underground organs such as corms, bulbs and rhizomes for reserving of nutrition and water until the conditions become better. Carnivorous plants: nitrogen-deficient plants have in at least seven distinct times become carnivorous, like: flypaper traps such as sundews and butterworts, spring traps-Venus fly trap, and pitcher traps in order to capture and digest insects to obtain scarce nitrogen. Pitcher plants: the pitcher trap evolved independently in three eudicot lineages and one monocot lineage. Similar-looking rosette succulents have arisen separately among plants in the families Asphodelaceae (formerly Liliaceae) and Crassulaceae. The orchids, the birthwort family and Stylidiaceae have evolved independently the specific organ known as gynostemium, more popular as column. The Euphorbia of deserts in Africa and southern Asia, and the Cactaceae of the New World deserts have similar modifications (see picture below for one of many possible examples). Sunflower: some types of sunflower and Pericallis are due to convergent evolution. Crassulacean acid metabolism (CAM), a carbon fixation pathway that evolved in multiple plants as an adaptation to arid conditions. C4 photosynthesis is estimated to have evolved over 60 times within plants, via multiple different sequences of evolutionary events.
== Plot == Jason sits on a bench in New York City waiting for someone to arrive. Jason's voiceover explains that he has been waiting for a long time, but to explain why, he needs to go back to the beginning. Jason tells the audience that every relationship reaches the "So..." moment, where someone in the relationship will want to take the relationship to a more serious place. At that point, Jason knows the relationship is over, as he is not ready for a serious relationship. Jason works with his best friend Daniel at a publishing house designing book covers. Their doctor friend Mikey, who has been married since the end of college, comes to them after his wife Vera requests a divorce. They decide to go out to a bar and celebrate Mikey now being single. The group meets up with Daniel's female wingman, Chelsea, as they try to get Mikey's mind off of his wife. Mikey meets a girl with glasses, while Jason meets Ellie, and hits it off with her after teasing another man that was trying to buy her a drink. Mikey gets "Glasses" number, but puts off calling her, resolving to work it out with Vera. Jason sleeps with Ellie, but leaves her apartment in a hurry after jumping to the mistaken conclusion that she is a prostitute. The next day, Jason and Daniel make a book cover pitch to a new author, who happens to be Ellie. Ellie is hurt and enraged that he did not stay the whole night. Jason tries to make it up to her, but she refuses. Jason, Daniel and Mikey then make a pact to stay single together for the foreseeable future.
Recently, a second parallel enzyme-dependent protective pathway was independently discovered by two labs that involves the oxidoreductase FSP1 (also known as AIFM2). FSP1 enzymatically reduces non-mitochondrial coenzyme Q10 (CoQ10), thereby generating a potent lipophilic antioxidant that suppresses the propagation of lipid peroxides. Vitamin K is also reduced by FSP1 to a hydroquinone species that also acts as a radical-trapping antioxidant and suppressor of ferroptosis. A similar mechanism for a cofactor moonlighting as a diffusable antioxidant was discovered in the same year for tetrahydrobiopterin (BH4), a product of the rate-limiting enzyme GTP cyclohydrolase 1 (GCH1). Hydropersulfides have been found to inhibit ferroptosis by acting as endogenous radical-trapping antioxidants.
=== Protein translocation and targeting === To exert their functions in the cell newly synthesized proteins must be targeted to the appropriate location in the cell, which is achieved by protein targeting and translocation systems. The growing polypeptide leaves the ribosome through a narrow tunnel in the large subunit. The region around the exit tunnel of the 60S subunit is very similar to the bacterial and archaeal 50S subunits. Additional elements are restricted to the second tier of proteins around the tunnel exit, possibly by conserved interactions with components of the translocation machinery. The targeting and translocation machinery is much more complex in eukaryotes.
Sources: en.wikipedia.org
Microwave burns are burn injuries caused by thermal effects of microwave radiation absorbed in a living organism. In comparison with radiation burns caused by ionizing radiation, where the dominant mechanism of tissue damage is internal cell damage caused by free radicals, the type of burn caused by microwave radiation is by heat—health effects colloquially associated with the term "radiation", such as radiation poisoning, cannot be caused by exposure to microwaves or other forms of non-ionizing radiation. Microwave damage can manifest with a delay; pain or signs of skin damage can show some time after microwave exposure.
Meanwhile, life cycle reversal, in which polyps are formed directly from medusae without the involvement of sexual reproduction process, was observed in both Hydrozoa (Turritopsis dohrnii and Laodicea undulata) and Scyphozoa (Aurelia sp.1). Anthozoa have no medusa stage at all and the polyps are responsible for sexual reproduction. Spawning is generally driven by environmental factors such as changes in the water temperature, and their release is triggered by lighting conditions such as sunrise, sunset or the phase of the moon. Many species of Cnidaria may spawn simultaneously in the same location, so that there are too many ova and sperm for predators to eat more than a tiny percentage — one famous example is the Great Barrier Reef, where at least 110 corals and a few non-cnidarian invertebrates produce enough gametes to turn the water cloudy. These mass spawnings may produce hybrids, some of which can settle and form polyps, but it is not known how long these can survive. In some species the ova release chemicals that attract sperm of the same species. The fertilized eggs develop into larvae by dividing until there are enough cells to form a hollow sphere (blastula) and then a depression forms at one end (gastrulation) and eventually becomes the digestive cavity. However, in cnidarians the depression forms at the end further from the yolk (at the animal pole), while in bilaterians it forms at the other end (vegetal pole). The larvae, called planulae, swim or crawl by means of cilia.
Mistaken diagnoses are sometimes very serious problems as physicians concentrate on treatment after a diagnosis is reached, not retracing the diagnostic analysis. Ideally, diagnoses are always correct, but disease variations are such that they are sometimes in error. In the case of diabetes, the tests are very clear. If you do not have high blood glucose at times (e.g., when fasting), you should not be diagnosed as diabetic, though perhaps as "prediabetic". Every one has higher glucose levels for one or two hours after eating food which contains some types of carbohydrates. Dialysis providing kidney function artificially. This requires an artificial kidney (a dialysis machine) and relatively long periods hooked up to the machine every few days. It is not equivalent to a working kidney, but is sufficient to maintain life, sometimes for extended periods. Diastolic blood pressure See: Blood pressure. Diet plan See: Meal plan. Dietitian An expert in nutrition who helps people with special health needs plan the kinds and amounts of foods to eat. In the US, a registered dietitian (R.D.) has special training and experience. The health care team for diabetes should ideally include a dietitian, preferably an R.D. Dilated pupil examination A necessary part of an examination for diabetic eye disease. Special drops are used to enlarge the pupils, enabling the doctor to view the retina at the back of the eye for damage. See funduscopy. Distal sensory neuropathy See: Peripheral neuropathy.
Vaginal rings are most commonly used for birth control purposes but can also be used to release compounds that treat and prevent STDs as well. The rings come in one standard size that fits most women and are made of flexible materials that contain the desired compound, whether that be hormones for birth control or other compounds for STD treatment. These substances are then slowly released over an extended period of time, typically a month. This is a convenient drug delivery method because they can easily be inserted and removed and do not prohibit intercourse. For birth control purposes, the vaginal ring is removed after 3 week and a new one is inserted a week later. Vaginal rings are also often used to treat symptoms of menopause, and these rings are replaced after a 3 month use. STD prevention and treatment through the use of vaginal rings is a newer application of such a device, but holds an advantage as a low maintenance option for women in areas with less access to regular healthcare.
Analysis of CRISPR sequences revealed coevolution of host and viral genomes. The basic model of CRISPR evolution is newly incorporated spacers driving phages to mutate their genomes to avoid the bacterial immune response, creating diversity in both the phage and host populations. To resist a phage infection, the sequence of the CRISPR spacer must correspond perfectly to the sequence of the target phage gene. Phages can continue to infect their hosts' given point mutations in the spacer. Similar stringency is required in PAM or the bacterial strain remains phage sensitive.
Sources: en.wikipedia.org
Gelatin is a partially hydrolyzed form of collagen that retains the ability to form gels in water. Collagen peptides undergo more extensive hydrolysis, resulting in shorter chains that dissolve in cold water without gelling. The two products differ in molecular weight distribution and functional behavior.
Bovine hide, porcine skin, fish skin, and poultry cartilage are common sources. The choice of raw material affects the amino acid profile and the resulting peptide sizes. Fish-derived collagen, for example, typically has a lower melting temperature than mammalian collagen.
No. Native collagen is an insoluble structural protein with a triple-helical conformation. Hydrolysis disrupts this structure, producing water-soluble peptides. The biological and functional properties of the peptides differ from those of the intact protein.
Size exclusion chromatography is the most common method, often coupled with detectors such as refractive index or ultraviolet. Mass spectrometry can provide more detailed sequence information for individual peptides.