Researchers have developed and created experimental samples of synthetic cells that are able to respond to external chemical signals in the same way as real living cells do. Experimental samples of synthetic cells begin to glow with fluorescent light when calcium ions appear in the environment. Calcium, in turn, is one of the main chemical signals used by living cells, and in this case it can be used for programming and real-time control of the operation of artificial cells.
“Using this approach, we can create artificial cells that, for example, having caught the chemical signs of cancer, immediately begin to synthesize the drug that is most suitable for this case,” says James Hindley, a biochemistry scientist at Imperial College in London, UK.
Artificial cells consist of several compartments surrounded by a common lipid membrane having microscopic pores.
Through these pores, calcium ions penetrate into the cell and activate the enzymes located there, which causes the phenomenon of fluorescence. This, of course, does not fully correspond to the complex biochemical processes that we can see inside living cells. Nevertheless, in such simple functions, a huge potential is hidden, which allows to solve even those tasks that go beyond the capabilities of living cells.
Such a simplification of the functions of artificial cells means that it will be much easier to work with these cells, and they will not be affected by various adverse factors that adversely affect the “health” of normal living cells. Moreover, correctly selected components placed inside artificial cells will allow deceiving living cells, forcing them to consider artificial cells to be real. This, in turn, will allow the creation of biological systems in which living and artificial cells will exist in complete harmony, performing one common task for all.
Solids are composed of atoms, molecules, and ions firmly bound together.
The properties of solids depend on the strength of the chemical bonds within them. Most solids have a crystalline structure.
Their particles – molecules, atoms or ions – are arranged in a strict order. Such a regular structure is called a spatial, or crystalline, lattice. Type of crystalline lattice of solids Ionic structure Molecular structure of solids Atomic structure Metal structure of solids Graphite conductivity is a rare example of a non-metal conductor Interesting experiments with carbon dioxide or hard ice
Type of crystalline lattice of solids The type of lattice depends on what particles are in the lattice sites.
There are 4 main types of spatial gratings – ionic, molecular, atomic and metallic. Particles in crystal lattices are not mobile, or constantly oscillate. With increasing temperature, the vibrational energy of particles of a solid increases, and when it exceeds the energy of intermolecular attraction, the crystal lattice is destroyed – melting occurs. Ionic structure Substances with an ionic structure, for example sodium chloride, usually have rather high melting points.
This property follows from the strong interaction between oppositely charged lattice ions.
molecular, atomic and metallic. Particles in crystal lattices are not mobile, or constantly oscillate. With increasing temperature, the vibrational energy of particles of a solid increases, and when it exceeds the energy of intermolecular attraction, the crystal lattice is destroyed – melting occurs. Ionic structure Substances with an ionic structure, for example sodium chloride, usually have rather high melting points. This property follows from the strong interaction between oppositely charged lattice ions.
Ionic substances are quite fragile
The force exerted by the crystal from the outside can shift the layers of ions, so that equally charged ions will be opposite each other. They will begin to repel, the layers will move apart, and the crystal lattice in this place will collapse.
The spatial model of the cubic lattice of the sodium chloride crystal is shown in the figure. Shown here are the relative sizes of the two types of ions and their location in space. Molecular structure of solids Atoms in the atomic lattice. Molecules are composed of atoms bonded by a strong covalent bond. For example, an iodine molecule consists of two atoms linked by the same covalent bond. The bonds between molecules and solids are not so strong. Iodine molecule I2. Solid iodine consists of iodine molecules bound in a regular crystal lattice.
Each iodine molecule consists of 2 iodine atoms firmly bound together.
In the solid state, iodine is a rather soft element, since the bonds between its molecules are weak.
Solids with a molecular structure melt, as a rule, at low temperatures.
During melting, covalent bonds do not break, only bonds between weakly interacting molecules are broken. Atomic structure Free carbon is known in two versions – diamond and graphite. Both diamond and graphite consist only of carbon atoms, however, these two substances have completely different structures. In graphite, a carbon atom is connected to 3 other atoms by short strong covalent bonds.
The 4th electron remains free, which determines the electrical conductivity of graphite.
Hexagonal rings form flat layers. The bonds between the layers are rather weak, and the layers can slide one relative to the other. That is why graphite is used as a solid lubricant. In a diamond, each carbon atom is bonded by strong covalent bonds to 4 other atoms. Billions of atoms are connected in a three-dimensional crystal lattice of unusual strength, which makes diamond the hardest known substance.
Undoubtedly, diamond is much less common than graphite, and much more valuable than it.
Both diamond and graphite consist only of carbon atoms, however, these 2 substances have completely different structures, and therefore, completely different compounds. The figure shows the structure of the diamond crystal lattice.
Salt crystals are composed of sodium ions and chloride ions. In the figure, the atoms are shown as balls.
The balls are conventionally spaced so that the three-dimensional structure of the crystal is visible. Pencil lead made of graphite. Weak attractive forces between the layers of carbon atoms allow the layers to slide relative to each other, which is why a graphite trace remains on paper. The metal structure of solids At the sites of substances with a metal lattice are positive ions and metal atoms, and between the nodes are electrons.
Atoms are densely packed in layers, and atoms of one layer are in the deepening of the neighboring layer. The interactions between atoms in such a structure are quite strong, and most metals have high melting points. Many electrons can move freely throughout the metal crystal, and therefore are called free electrons. Free electrons have a negative charge and attract metal cations, as a result of which the crystal lattice of metals is stable.
Free electrons can freely transfer heat and electricity, so they are the cause of the main physical properties that distinguish metals from non-metals – high electrical and thermal conductivity.
Unlike ionic substances, metals are plastic and malleable – metal layers can slip relative to each other without destroying the spatial lattice. Solid metal atoms are tightly packed. External electrons move freely and are evenly distributed between all atoms.
A single electron cloud firmly binds atoms to each other. When an electric current passes through a metal, the total electron flux has a certain direction – from the negative pole to the positive.
Graphite conductivity is a rare example of a non-metal conductor. Electric current is a directed flow of charged particles. These charged particles can be ions or electrons that can move freely. In some cases, the ability of a material to conduct or not conduct electric current allows us to judge its structure.
Graphite is a rare example of a non-metal conductor.
In practice, it is used as conductive “brushes” in a power tool. Graphite conducts current, since each carbon atom in its structure is covalently bonded to only 3 other atoms. Thus, 1 (4) electron at each atom remains relatively free, taking part in the formation of bonds, “Smeared” over the entire layer of atoms. Such a connection is called delocalized.
It is an electron source capable of moving freely through graphite layers to conduct an electric current. An interesting video, which clearly shows not only the conductivity of graphite, but also the formation of an electric arc between graphite rods.
When substances with ionic bonds (salts) are molten or dissolved in water, the crystal lattice is destroyed, ions become free and can conduct electricity.
This phenomenon helped scientists in their time to understand that ionic substances consist of charged particles. Interesting experiments with carbon dioxide or solid ice
An experiment was conducted in the video in which 90 dry ice was poured into an inflatable pool. At -78.5 0С solid carbon dioxide (dry ice) turns into carbon dioxide, bypassing the liquid state. If dry ice is thrown into water, it will begin to evaporate. A mixture of dry ice and water is used for stage effects (thick fog).
After many years of effort, the international team of scientists managed to grow the laboratory culture of the archaea Lokiarchaea. Prior to this, micro-organisms have been known and , as far as possible , been studied only scraps of DNA , extracted from the bottom silt from the bottom of the Atlantic.
Lokiarchei are peculiar microbes from the Archaean group, resembling bacteria, but arranged much simpler. Many scientists believe that a couple of billion years ago they became the ancestors of eukaryotes – organisms with a cell nucleus. From them subsequently came all the diversity of life that we now see: from a person to a sponge.
Lokiarchei, more precisely, traces of their presence, were isolated from bottom sediments Loki castle – the zone known at the bottom of the Atlantic Ocean, known as hydrothermal sources, between Greenland and Norway at a depth of 2300 meters. It was opened in 2005 and the uniqueness of its conditions prompted scientists to analyze the samples collected from the bottom in order to recreate the appearance of the microbes living on the basis of genetic material.
Among the genomes identified in this way, one stood out, combining the genes of prokaryotes, i.e.,nuclear-free unicellular organisms, and eukaryotes, which already have a cell nucleus. The discovery of his DNA was a significant event, however, it was necessary to make sure that such a microbe really exists, and is not a mistake made as a result of contamination with extraneous genetic material.
The proof of this could only be a full-fledged living culture of the microbe. But – getting it turned out to be very difficult. Not only that, our relic lives in very specific conditions – in very hot water and at high pressure. It also reproduces very slowly. Like all normal protozoa, this happens by dividing the cells in half, into two new ones, but the speed of this process is much lower than that of the more familiar microorganisms.
“This is one of the slowest-dividing microorganisms I know of,” says Thijs Ettema, an evolutionary microbiologist at the University of Wageningen in the Netherlands.
It took 5 years to wait for the slow growth of lociarchae in a special bioreactor that maintained high temperature and the methane content typical for Loki Castle. Another year was needed to propagate the barely manifested culture in test tubes.
Finally, after many years of work, the researchers created a stable laboratory culture containing only two types of archaea. One of them is the target lociarchaeus, the second produces the methane needed for it. Together, two microbes formed a symbiotic relationship (similar colonies of bacteria and archaea were observed earlier). Scientists called this culture the Lokiarchaeon Prometheoarchaeum syntrophicum.
Fig. 1. Sundyrsky gorynych (Gorynychus sundyrensis) caught the amphibian of the dvinosaurus (Dvinosaurus) . Drawing by Andrey Atuchin
The Sundyr locality, located on the shore of the Cheboksary reservoir on the border of Chuvashia and Mari El, has a unique “transitional” character: it contains the remains of animals buried during the global faunal restructuring that took place in the middle of the Permian period. Russian paleontologists, having studied the finds made at this location over the past couple of years, described two new carnivorous animals from the group of terocephals. These species are more advanced in an evolutionary sense than all those who have been found in Sundyr before.
In the Permian period, various animals were already roaming overland on land. Many of the Perm tetrapods (four-legged animals) have already been told by the “Elements” more than once (see, for example, the news of Gorynych and the night-night – new Permian predators from the banks of the Vyatka , “Elements”, 08/20/2018; Permian period park: found in Sardinia three types of synapsids , “Elements”, 11/14/2018 and pictures of the day Bilateral chalcosaurus , Erasaurus and Suminia and Sabretooth beast -dog ). Paleontologists distinguish three main faunistic tetrapod groups, which successively replaced each other during the Permian period, and name them according to the group that dominated the corresponding time interval.
In the first third of the Permian period, the pelicosaurus fauna flourished on land. Pelicosaurus were the most ancient and primitive synapsids , among them there were both herbivorous and predatory forms. Of these, the “sailing lizards” are the most famous: pelicosaurs and edaphosaurus (they are called “sailing” for their characteristic appearance: on their back they had a rather large crest of skin stretched over huge spinous processes of the vertebrae, Fig. 2).
Fig. 2. Large representatives of the Permian fauna. On the left is the Edaphosaurus edanosaurus boanerges , on the right is the Estemmenosuchus uralensis . These animals could reach 4 meters in length. Drawings from ru.wikipedia.org
In the second third of the Permian period, the pelicosaurus fauna was replaced by the dinocephalic fauna. The most noticeable and widespread tetrapods were descendants of pelicosaurs – dinofephals (among which there were also herbivorous and predatory animals). Dinocephals were distinguished by large sizes, greater adaptability to terrestrial life, and as a whole had a more complex organization. Their distinctive feature was the thick bones of the skull, according to which the animals got their name – “scary-headed”. Bright representatives were herbivorous dinotsefalov ulemosaurus and estemmenosuchidae , predatory – titanofon (Titanophoneus) .
The third and last fauna of the Permian period is the periodontium. The dominant position in it was occupied by the bestial-toothed reptiles of theiodont . According to the paleontologist M.F. Ivakhnenko , they came from the ancient synapsids and were a kind of alternative line in relation to dinocephals.
Almost all the locations of Permian fossils are confined to only one of these groups. But there are rare, even unique locations of a peculiar “transitional type” in which the remains of animals from different groups are found. One of them is located on the banks of the Cheboksary reservoir, on the border of Chuvashia and the Mari El Republic, near the village of Bolshoi Sundyr .
Here, on the high bank of the reservoir, red-colored rocks of 260 million years old are exposed (Fig. 3). The fauna found in them represents a transitional stage between the dinocephalic and theriodontic groups: dinocephalic and theriodonts were found here, the remains of amphibians also belong to more ancient and later taxa (V.K. Golubev et al., 2015. About age Sundyr faunistic complex of Perm tetrapods of the East European platform ).
Fig. 3. Excavations at the Sundyr site and a view of the Cheboksary reservoir. Photo by Olesya Strelnikova, 2018
Excavations at the Sundyr site began in 2010 and are still ongoing. During this time, employees of the Paleontological Institute of the Russian Academy of Sciences collected about seven hundred diagnosed tetrapod remnants there . Most of them belonged to amphibians, mainly to dvinosaurs (Dvinosaurus) , which account for 35% of all bones found.
Fig. 4. The bone remains from Sundyr are mostly small and look unrepresentative like this piece of bone. Photo by Julia Suchkova
16% of the remains found belong to predatory lizards: these are mainly teeth and cranial bones. Previously, these predators were defined as dinofephals close to giant titanophones (Fig. 5). Then, the bones of more advanced predatory gorgonopies, characteristic of the theriodont group, were found at the site. There was an assumption that both carnivorous dinocephals and carnivorous gorgonopies lived here at the same time, which corresponded to the transitional nature of the location.
Fig. 5. On the left – a predatory titanophone attacks the herbivorous tapinocephalus, illustrated by S. Krasovsky from an article by A. Nelikhov Blue Bones ( National Geographic Russia , No. 12 for 2012). On the right is the cub of another predator of those times – gorgonopia, illustration by A. Atuchin from the book Ancient Monsters of Russia
However, new finds from the past two years and re-examination of old finds have changed the picture. At first it became clear that there were no predatory dinocephals in the whereabouts. The remains, which were previously defined as titanophones, belonged to other, more advanced forms – terocephals . A further audit of the remains showed that there were no gorgonopies in Sundyr either. All diagnosed predator bones belonged to terocephals. But the herbivorous lizards and a number of amphibians actually belonged to the dinocephalic fauna, so that the “transitional” character of Sundyr did not go away.
Such taxonomic studies are unlikely to be entertaining to an outsider, although in reality we are talking about very serious reevaluations. Imagine that one archaeologist finds a bone and claims that it belongs to a modern person, another believes that it is an Australopithecus bone, and then it turns out that it is from a kangaroo.
According to new studies by Russian paleontologists, all the discovered remains of carnivorous dinosaurs from Sundyr belong to two previously unknown, very large terocephals. The predator, whose remains were found more frequently, was described as a new genus and species of the yognathus crudelis (Julognathus crudelis) , which can be translated as the “ruthless Volga jaw” (Yul – the ancient Mari name of the Volga). To date, 81 teeth and a fragment of skulls of ylognatus have been found (Fig. 6).
Fig. 6. Reconstruction of the skulls of Julognathus crudelis ( above ) and Gorynychus sundyrensis . Images from discussed articles in the Paleontological Journal
The animal was one of the largest predators of the Permian period. Judging by some fragments, the skull of the ylognatus reached a length of 43 centimeters, that is, it was two times longer than that of a wolf. The animal itself was apparently the size of a bear.
The second lizard belongs to the recently described genus Dragon ( Gorynychus ), but differ in the dental system and has been allocated to a new species – Dragon sundyrsky (Gorynychus sundyrensis) . His remains were less common: 33 bones were found that reliably belonged to him. It was similar in size to the ylognatus, but had a more massive and shortened skull (Fig. 6, bottom).
One cranial fragment of the mountain revealed a curious feature associated with the change of fangs. All animal hunters – both carnivorous and herbivorous – had regular tooth changes throughout their lives: old ones fell out, new ones grew. The shift models were different. The fang and the related African lycosuchids, the new fangs completely grew in advance, even before the old ones fell out, and for some time four upper fangs sat in the mouth at once. Then the old pair of fangs fell out, and next to the remaining, new interchangeable fangs began to grow. Among the jaw bones of lycosuchids, almost 40% of the findings are with double fangs. Now such a model of tooth changes has been found in European terocephals.
Gorynich’s teeth presented another discovery. They show a strong intravital attrition (on the teeth of the ylognatus it is not). The animals obviously used their teeth to work with very hard material (most likely they gnawed bones). Such eating behavior was unusual: the dental apparatus of most Perm predators was cutting, and not tearing. The predator plunged large fangs into the body of the victim and, as it were, cut a piece of meat, but he could not tear off a small piece, as dogs, for example, are doing now. Therefore, large predators hunted for prey comparable to their size. M.F. Ivakhnenko joked that the Permian beastmaker could eat a hippo, but could not cope with a hare.
In Permian sediments, bones with traces of bites are extremely rare. There are such bones in the Sundyr location, and this is the only one of more than two hundred locations in Eastern Europe where the bones were found. The find confirms the opinion that it was the terocephalus who developed the tearing type of dental apparatus, which gave them the opportunity, among other things, to gnaw bones and provided a serious evolutionary advantage.
Sources: 1) Yu. A. Suchkova, V.K. Golubev. New primitive terocephalus (Therocephalia, Theromorpha) from the Middle Perm of Eastern Europe // Paleontological journal . 2019. №3. DOI: 10.1134 / S0031031X19030176. 2) Yu.A. Suchkova, V.K. Golubev. New Permian terocephalus (Therocephalia, Theromorpha) from the Sundyr complex of Eastern Europe // Paleontological journal . 2019. №4. DOI: 10.1134 / S0031031X19040123.
A press conference convened in Tokyo on March 7 by the International Committee on Future Accelerators (ICFA) to clarify the situation around the ILC project.
The future of the International Linear Collider ILC, one of the main hopesto a new breakthrough in particle accelerator physics is still foggy. In technical terms, the collider project has long been ready, the technologies have been developed and demonstrated, and the question of starting construction has moved from the scientific and technical plane to the economic one. The main obstacle to the implementation of ILC for several years now remains the uncertain position of the Japanese government, caused by the high cost of the project. On the one hand, Japan understands the importance of ILC both for all particle physics and for the development of science and technology within the country. But the government is not ready to take on all the multibillion-dollar costs of building a collider without guaranteed significant financial contribution from Europe, the United States and other countries. The international community, in turn, strongly expresses its readiness to share difficulties and costs, if Japan starts to implement ILC. However, neither side has yet submitted an official document binding on actions and expenses. Despite years of intensive negotiations, there is still no clear statement from the Government of Japan about its readiness to take on the bulk of the costs.
In 2018, negotiations seemed to be on the home stretch, and the scientific community was awaiting a final decision by mid-December (see the review of the situation in the news on Elementary Particle Physics in 2018 ). However, no clear statement was made by Japan then, although it was once again emphasized that the Japanese government understands the importance of the project and continues to conduct intensive negotiations. It was expected that the decision will be announced on March 7-8, 2019, when the next, 83rd meeting of the International Committee on Future Accelerators ( ICFA ) will be held in Tokyo .
On March 7, as part of the ICFA meeting, a press conference was held on the current situation around the ILC. Initially, Jeffrey Taylor, chairman of the ICFA, made public the message that the Japanese Ministry of Education, Culture, Sports, Science and Technology ( MEXT ) transmitted to the ICFA just a day before. It can be reduced to two points: 1) Japan is interested in the implementation of ILC, but is currently not ready to give the green light for the construction of a collider in a selected location. 2) Japan begins formal negotiations with international partners (countries and laboratories) on the allocation of costs and consideration of alternative locations for the collider.
Then, for an hour, Jeffrey Taylor, as well as Tatsuya Nakada, Chairman of the Linear Collider Board Committee, and Masanori Yamauchi, head of KEK’s largest Japanese laboratory, answered questions from the press and clarified the positions of the parties. So, “not ready” does not mean yet “refuses”; Japan continues to consider all possibilities. Also, for the first time, a clarification “in a chosen place” was made, but this may mean both a preference to build an ILC in another place in Japan and a willingness to invest money only if another country takes over the construction.
It should be clarified that when the ILC construction site was discussed in the early 2010s, there were several proposals (including from Russia), and the Japanese was chosen as the most “safe” in technical, scientific and economic terms. Alternative proposals have not disappeared, they, in principle, can be reanimated. However, over the past time, the general situation in accelerating particle physics has changed. Literally in the last year or two , several projects have gained clear contours at once.electron-positron colliders, capable of working as a Higgs factory and getting about the same scientific results as ILC. Of course, ILC is still the most elaborate project, and if Japan undertakes its construction, ILC will enter service earlier than its competitors. In addition, unlike cyclic accelerators, a linear collider always has the opportunity to increase energy by lengthening the acceleration path. However, ILC has already lost its exclusivity status, and if the question of transferring ILC to another place is raised by the edge, the scientific community can already find a replacement for it. However, a reservation immediately followed that the ICFA would make every effort to implement ILC elsewhere.
As for the ongoing negotiations with international partners, there is also a nuance. So far, all visits and negotiations have been informal. Now Japan has opened the way to official negotiations with the United States, European countries and major international organizations. Details of the planned negotiations are not yet known. In addition, MEXT wants to make sure at the official level that there is complete consensus in the scientific community within Japan regarding the construction of ILC.
Overall, the ICFA and the international community took the message from MEXT with some disappointment. No specific new deadline has been appointed, although the ICFA chairman expressed the hope that Japan will finally be determined within a few months. Japan understands the changed situation in collider physics and the danger that if the decision is delayed for another couple of years, the chances of full support from international partners will decrease.
Further details regarding the press conference and the whole situation can be found, for example, in the LCNewsLine and Iwate & the ILC twitter accounts .
