Июль 2022 г.

Российская наука и мир (по материалам зарубежной электронной прессы)

CONTENTS / ОГЛАВЛЕНИЕ


• Crushed, zapped, boiled, baked and more: Nature used 57 recipes to create Earth’s 10,500+ "mineral kinds"
• Mummified mystery pup that died 18,000 years ago was a wolf
• Russian scientists have created an antibacterial and environmentally friendly hydrogel
• Les parures en os humain de 8000 ans du lac Onega, en Russie
• Cette météorite cachait des cristaux de graphite inconnus sur Terre
• US renews space flights with Russia in rare cooperation
• New kind of black silicon shows improved light-trapping properties
• Siberia's rivers will be filled with fish
• Researchers learn how ozonation treats RAS water
• Russian scientists synthesize new antimicrobial platinum compounds

Исследователи из Института Карнеги, Кольского научного центра РАН и Аризонского университета опубликовали статью по результатам пятнадцатилетнего исследования. В ней ученые предложили новую классификацию существующих на Земле минералов, учитывающую не только их кристаллическую структуру и химический состав, но и способ происхождения. Всего таких способов выделено 57, причем 40% минералов природа создала более чем одним способом. Согласно этой классификации количество минеральных видов составляет 10556, тогда как в существующий на данный момент перечень входит около 6000 видов.

A 15-year study led by Carnegie’s Robert Hazen and Shaunna Morrison details the origins and diversity of every known mineral on Earth, a landmark body of work that will help reconstruct the history of life on our planet, guide the search for new minerals and ore deposits, predict possible characteristics of future life, and aid the search for habitable exoplanets and extraterrestrial life.
For more than a century, thousands of mineralogists from around the globe have carefully documented "mineral species" based on their unique combinations of chemical composition and crystal structure. Carnegie scientists Robert Hazen and Shaunna Morrison took a different approach, emphasizing how and when each kind of mineral appeared through more than 4.5 billion years of Earth history.
In twin papers published by American Mineralogist, Hazen, Morrison, and their collaborators detail how they used extensive database analysis to cluster kindred species of minerals together and distinguish new mineral species based on when and how they originated, rather than solely on their chemical and physical characteristics.
Their work indicates that the number of "mineral kinds" - a term coined in 2020 by Hazen and Morrison - totals more than 10,500. In comparison, the International Mineralogical Association recognizes about 6,000 mineral species on the basis of crystal structure and chemical composition alone.
"This work fundamentally changes our view of the diversity of minerals on the planet," Hazen explained. "For example, more than 80 percent of Earth’s minerals were mediated by water, which is, therefore, fundamentally important to mineral diversity on this planet. By extension, it explains one of the key reasons why the Moon and Mercury and even Mars have far fewer mineral species than Earth."
"It also tells us something very profound about the role of biology," he added. "One third of Earth’s minerals could not have formed without biology - shells and bones and teeth, or microbes, for example - or the vital indirect role of biology - importantly by creating an oxygen-rich atmosphere that led to 2,000 minerals that wouldn't have formed otherwise. Each mineral specimen has a history. Each tells a story. Each is a time capsule that reveals Earth's past as nothing else can."
According to Hazen and Morrison - along with collaborators Sergey Krivovichev of the Russian Academy of Sciences and Robert Downs of the University of Arizona - nature created 40 percent of Earth’s mineral species by more than one method - for example, many minerals arose both abiotically and with a helping hand from living organisms - and in several cases more than 15 different "recipes" produced the same crystal structure and chemical composition.
Of the 5,659 mineral species surveyed by Hazen and colleagues, nine arose via 15 or more origin pathways, each incorporating various combinations of physical, chemical, and biological processes - everything from near-instantaneous formation by lightning or meteor strikes, to changes caused by water-rock interactions or high-pressure, high-temperature transformations that took place over hundreds of millions of years.
And, as if to demonstrate a sense of humor, nature has used 21 different ways over the last 4.56 billion years to create pyrite, also known as Fool’s Gold - the most origin stories of any mineral. Pyrite, composed of one part iron to two parts sulfide, is so stable that it forms under a huge variety of circumstances, including meteorites, volcanos, hydrothermal deposits, by pressure between layers of rock, near-surface rock weathering, in microbially-precipitated deposits, and via several mining-associated processes.
To reach their conclusions, Hazen and Morrison built a database of every known process of formation of every known mineral. Relying on large, open-access mineral databases, amplified by thousands of primary research articles on the geology of mineral localities around the world, they identified 10,556 different combinations of minerals and modes of formation.
"No one has undertaken this huge task before," said Hazen, who honored last year by the IMA with its medal for his outstanding achievements in mineral crystal chemistry, particularly in the field of mineral evolution. "In these twin papers, we are putting forward our best effort to lay the groundwork for a new approach to recognizing different kinds of minerals. We welcome the insights, additions, and future versions of the mineralogical community."
The papers’ groundbreaking observations and conclusions include:

Щенок, живший 18 тысяч лет назад и найденный мумифицированным в вечной мерзлоте Якутии в 2018 г., оказался волчонком, причем генетически довольно далеким от ранних собак. Международная команда ученых, в том числе российских, установила это, проанализировав геном щенка, а также геномы 72 древних волков Евразии и Северной Америки. Кроме того, выяснилось, что волчьи популяции были тесно связаны между собой независимо от места обитания, при этом ни одну из них нельзя назвать прямыми предками собак.

A mummified pup discovered in Siberia is not a dog, new research finds. Rather, the cute-and-cuddly canine is actually a young wolf.
In a new study aimed at understanding dog domestication, researchers analyzed the genome of the puppy, along with the genomes of 72 ancient wolves. The pup, which was found in the Siberian permafrost in 2018 and whose lineage has been debated ever since, was nicknamed "Dogor" and was fully intact, with pettable fur and unbroken whiskers. At first, scientists couldn't tell if the 18,000-year-old pup was a wolf or a dog, but the new analysis revealed that it was a wolf - and that it was not very closely related to the earliest dogs.
"We know that dogs were the first animal to be domesticated way back in the ice age," said Anders Bergström, a postdoctoral fellow in ancient genomics at the Francis Crick Institute in London. But other aspects of their domestication are some of the big mysteries of human prehistory, he told Live Science. "We don't know where in the world it happened," Bergström said. "We don't know what human group was involved, and we don't know whether it happened once or multiple times."
Wolf to woof
Dogor's genome was one of 66 never-before-sequenced ancient wolf genomes studied by Bergström and his colleagues, who also looked at the genomes of five previously sequenced ancient wolves and one ancient dhole, another type of wild dog that is still found today in parts of Asia.
The researchers were looking for hints as to where domesticated dogs (Canis lupus familiaris) came from. Clearly, dogs were domesticated from wolves (Canis lupus), but the genes of modern wolves have shifted too much over the ages to reveal which wolves dropped their wild ways to team up with humans. To pinpoint the closest wolf ancestors of the first dogs, Bergström said, it's important to look at wolves from the time when dogs were being domesticated - between about 30,000 years ago and 14,000 years ago.
The 72 samples covered 100,000 years of prehistory in Europe, Siberia and northwestern North America. The genomes revealed that wolves thrived throughout the ice age, with a globally connected population. The most intriguing results, however, had to do with the transition from wolf to dog. The researchers found that dogs are more closely related to ancient wolves from eastern Eurasia than to ancient wolves from western Eurasia.
"This suggests to us that probably domestication happened somewhere in the East, somewhere in Asia, and probably not in Europe," Bergström said. "However, Asia is, of course, very large; we can't really narrow down with more precision where it happened."
Northeast Siberia, where Dogor was found, does not appear to be ground zero for the genetic transition, Bergström said, as wolves from this region aren't closely related to the oldest dogs. But there are many other areas in Asia where ancient wolf DNA has yet to be collected and studied, so it's possible the pre-dog wolves came from a spot that has never been sampled.
A fuzzy tale
Genomic analysis also told the researchers that dogs from the Near East and Africa get a chunk of their genes from an unknown western Eurasian source. There are two possible explanations for this. The first is that dogs were domesticated in Asia, and as they moved westward, they mixed with local wolf populations, bringing in western Eurasian wolf genes. Another explanation could be that domestication occurred twice, in both an easterly and more westerly location, and that dogs from these two domestication events eventually mixed.
Whatever happened, Bergström said, it must have occurred before 7,200 years ago, which is the age of the oldest dog found in the Near East. That specimen had both the eastern and western gene contributions.
"By getting even earlier dog genomes from the Near East or that general region, we might be able to say more about whether it was a single [process] or two domestication processes," Bergström said.
The results were published June 29 in the journal Nature.

Петербургские ученые разработали антибактериальный гидрогель для лечения ран и ожогов из биоразлагаемой целлюлозы из отходов сельхозпредприятий. Гидрогель экологичен, не токсичен и прост в производстве.

The press service of the St. Petersburg Technical University reported that university scientists have created a biodegradable hydrogel based on cellulose waste from agricultural enterprises for the treatment of wounds.
The department notes that the hydrogel, which was invented by university scientists in collaboration with scientists from the Institute of Macromolecular Compounds, differs from others in that it does not contain toxic substances, since it consists only of natural materials.
"Most of the hydrogels that exist today are synthetic and contain toxic ingredients, and are usually made from non-renewable materials - materials based on oil. The hydrogel we created has bioecological properties and is not toxic to humans," the report says. Alexander Michaelidi, Associate Professor at the University.
He adds that only natural, biodegradable materials derived from agricultural waste are used in the production of this hydrogel, and wood pulp is not used to reduce the burden on the environment. The technology of its production is very simple, as cellulose powder is placed in a special solution, and within seven days its molecules turn into a hydrogel, after washing the solvent is removed and a clean and transparent watery hydrogel remains. To give antibacterial properties, silver nanoparticles are added to prevent irritation. Cellulose also has the ability to absorb impurities in the wound.
The innovators hope that with the help of this hydrogel it is possible not only to treat wounds and burns, but also to produce implants, smart capsules for the delivery of active substances in targeted drug therapy.
The hydrogel can be produced directly in farms, where it can also be used to retain moisture in the soil and deliver fertilizer to plant roots.

Часть подвесок возрастом 8200 лет, обнаруженных в 1930-х годах на Южном Оленьем острове в Карелии, оказались сделаны не из костей животных, как считалось ранее, а из человеческих. Это первая находка такого рода в регионе.

Une étude vient de livrer la première preuve d'utilisation d'os humains dans la fabrication de pendentifs chez les chasseurs-cueilleurs d’il y a plus de 8000 ans au Nord-Est de l'Europe.
Griffes, dents, plumes, coquillages… Les raisons pour lesquelles les hommes et les femmes de la préhistoire se paraient sont sans doute multiples. Portés à même le corps ou cousus sur des vêtements comme ornements, ils ont pu marquer une appartenance à un groupe, ou répondre à des raisons symboliques, voir les deux à la fois. Et c’est souvent parce qu’ils les emportaient dans la mort que nombre de ces parures ont pu être retrouvées dans des sépultures et ainsi parvenir jusqu’à nous. En général, ces pendentifs étaient fabriqués à partir de dents et d’ossements d’animaux, qu’il s’agisse de mammifères, d’oiseaux, de poissons ou de mollusques. Mais comme vient de le rappeler une étude publiée dans le Journal of Archaeological Science, il est arrivé que des os humains soient également utilisés comme matière première.
Des os humains dans les parures
C’est le cas de pendentifs vieux de 8.200 ans, découverts il y a 80 ans sur l’île de Yuzhniy Oleniy Ostrov, en Carélie russe, que de récentes analyses ont révélé être en os humain alors qu’ils avaient jusque-là étaient considérés comme des os d’animaux. De précédentes études sur ce même site avaient déjà permis en 2021, de décrire l’usage de dents de wapiti pour produire des sons à destination de danses ou de rituels. Située sur le lac Onega, au nord-ouest de la Russie, la nécropole mésolithique étudiée par l’archéologue russe J.F Ravdonikas entre 1936 et 1938, a livré de très nombreuses parures dans un site où 177 tombes ont été exhumées.
Les analyses effectuées à l’époque avaient détaillé la présence de pendentifs réalisés à partir de dents, en particulier d’incisives d’élan d’Eurasie - aussi connu sous le nom de wapiti (Alces alces), de castor (Castor fiber) et de canines d’ours brun (Ursus arctos). Mais parmi les objets confectionnés, certains étaient clairement en os, et Kristiina Mannermaa, professeur à l’Institut des sciences (HELSUS) de l’Université d’Helsinki (Finlande), ainsi que ses collègues, ont souhaité identifier précisément les os des animaux privilégiés par ces populations du mésolithique (cette période européenne charnière de 10.000 à 5.000 ans avant notre ère, qui a connu une modification profonde du climat et de l’environnement). Pour ce faire, ces ensembles ont été envoyés au centre de recherche BioArch de l’Université de York, en Grande-Bretagne, afin d’être soumis à des analyses zooarchéologiques par spectrométrie de masse (ou ZooMS). Une technique qui permet d’identifier des espèces à partir de peptides, ou d’acides aminés, extraits des protéines contenues dans les échantillons d’os.
A Yuzhniy Oleniy Ostrov, des ornements en os ont été rencontrés dans 22 sépultures. Et parfois en grand nombre dans une seule et même tombe. C’est ainsi que 6 d’entre elles ont livré 37 fragments d’os longs façonnés en pendentifs. "Ces résultats ont été surprenants", avoue Kristiina Mannermaa, dans un communiqué de l'Université d'Helsinki. "12 des 37 échantillons envoyés se sont avérés être humains". Il s’agissait en particulier d’éclats d’os longs. Et ces éléments d’origine humaine étaient mêlés à ceux d’animaux.
La plus ancienne utilisation d'os humain en ornement dès l'Aurignacien
"L’emploi de restes humains dans des parures sont décrits en Asie, autant qu’en Amérique du Sud, et en Europe", rappelle Kristina Mannermaa. En Scandinavie, des dents humaines perforées ont par exemple été recueillies au Danemark dans des tombes de 6.000 avant J.-C., à Bogebakken, ainsi qu’en 1943, dans un autre site de 9.000 ans, à Svaerdborg. De même qu’en Anatolie centrale (Turquie), il y a plus de 7.000 ans. Le plus ancien usage d’os humain comme matière première pour façonner des ornements remonterait néanmoins à des sites aurignaciens (35.000 ans) en France, ainsi qu’autour de 29.000 ans, à Pavlov et Dolni Vestonice, en République tchèque. Ceci pour rester uniquement dans le cadre de parures et ornements, puisque l’adoption d’os pour en faire des outils, est connue dès l’époque moustérienne (Paléolithique moyen), comme à La Quina (53.000 ans-33.000 ans), en France, où des fragments de crâne ont servi de retouchoir (outil en os utilisé pour modifier un éclat de pierre).
"L’utilisation d’os humain étant souvent associé à des cas de cannibalisme, à l’instar de ce qui avait été trouvé dans la grotte de Cough au Royaume-Uni (vers 12.700 ans avant J.-C.) nous avons cherché à identifier d’éventuelles traces de découpe sur les os des parures de Yuzhniy Oleniy Ostrov", explique Kristiina Mannermaa. Mais l’usure des objets était telle qu’il a été impossible d’y distinguer la moindre marque potentielle. "Le fait que l'utilisation d'ossements humains n'ait été soulignée d'aucune façon lors des précédentes études et que ces objets soient indétectables par rapport à ceux faits à partir d'os animaux, peut aussi caractériser l'entremêlement de ce qui était d’origine animale ou humaine dans les représentations du monde que pouvaient avoir les hommes et femmes de la préhistoire", a ainsi résumé Kristinna Mannermaa. Des périodes, sans doute, où les humains et les animaux n’étaient pas perçus comme des entités distinctes et où la vie était fondée sur des interactions entre toutes sortes d’êtres, qu’ils soient humains ou non-humains. "Nous savons qu’un tel brouillage des formes et des frontières a fait et fait toujours partie de la vision du monde de peuples autochtones", a ajouté Kristinna Mannermaa. Ce qui est encore le cas parmi de nombreux groupes, à l’instar des Achuars, ou Jivaros, (Equateur), en Amérique du Sud. Les parures en os humain auraient pu aussi être conservées en tant que reliques d’un ancêtre ou d’un membre de la famille. Sans oublier qu’il ait pu aussi parfois s’agir de trophées pris sur un ennemi tué.
Financée par la Fondation Kone (Finlande) et le Conseil européen (ERC), cette étude à laquelle participent des chercheurs de l’Académie des Sciences russes fait partie du programme "Animals Make Identities" de l’Université d’Helsinki (Finlande) : un projet qui étudie les liens sociaux entre les humains et les animaux à partir du matériel funéraire recueilli dans les sépultures des chasseurs-cueilleurs du Nord-Est de l’Europe.

Анализ пылевых частиц метеорита, взорвавшегося над Челябинском 15 февраля 2013 г., показал наличие необычных кристаллов, оказавшихся ранее неизвестной формой углерода.

Des chercheurs de l’université nationale des sciences de Moscou ont partagé les résultats de l’étude de la météorite dite de Tcheliabinsk, dans la revue The European Physical Journal Plus. L’analyse de minuscules grains de poussière au microscope électronique, puis aux rayons X, a permis d’identifier une forme cristalline inconnue sur Terre.
Des cristaux de graphite inconnus dans le superbolide de Tcheliabinsk
Le 15 février 2013, une météorite emportant avec elle des cristaux de graphite inconnus illumine le ciel et se désintègre en Russie à proximité de la frontière avec le Kazakhstan. L’objet est un superbolide dont la taille est estimée entre 15 m et 17 m pour une masse de 12 000 tonnes. En pénétrant l’atmosphère terrestre à une vitesse de 19 km/s, l’objet se fragmente à une altitude comprise entre 20 et 40 kilomètres et libère une énergie colossale estimée par le Jet Propulsion Laboratory de la NASA à plus de 440 kilotonnes de TNT soit plus de 30 fois l’énergie dégagée par l’explosion de la bombe atomique d’Hiroshima. L’onde de choc produite fait voler en éclats des milliers de fenêtres de Tcheliabinsk et détruit un mur et le toit d’une usine.
La désintégration de la météorite produit une grosse quantité de minuscules météorites et un panache de poussière qui reste plusieurs jours en suspension dans l’atmosphère avant de se déposer au sol. Une collision de plaine masse qui aurait pu avoir des conséquences catastrophiques est ainsi évitée.
Le 30 juin 1908 déjà, une explosion similaire s’était produite en Sibérie avec des conséquences bien plus importantes pour la région. La puissance est cependant plus importante que celle de Tcheliabinsk. En effet, les experts l’estiment à une centaine de fois la puissance de la bombe atomique d’Hiroshima. Le souffle de l’explosion rasa complètement une région de plus de 2000 km2 et renversa plus de 80 millions d’arbres aussi facilement que de simples brins d’herbe.
Des fragments de la météorite difficiles à retrouver
Bien souvent lorsqu’une météorite pénètre dans l’atmosphère terrestre, il est assez difficile de retrouver des fragments. L’échauffement produit par la rentrée atmosphérique du bolide le consume presque entièrement. Ne laissant derrière lui qu’une faible quantité de poussière. Cette poussière finit par retomber à un moment donné sur le sol, mais sa localisation reste très difficile, voire impossible.
Dans le cas de la météorite de Tcheliabinsk, de nombreux vidéastes amateurs ont pu filmer le moment où elle entre dans l’atmosphère. Ce qui a permis aux scientifiques de reconstituer sa trajectoire avec une bonne précision.
De plus, ce n’est pas tous les jours que des météorites de 15 à 17 mètres de diamètre pénètrent l’atmosphère terrestre. Même si la Terre est régulièrement « bombardée » par des météorites, il s’agit le plus souvent de spécimens de petites tailles. Ces derniers finissent par être entièrement consumés lors de leur traversée de l’atmosphère.
La météorite de Tcheliabinsk était suffisamment volumineuse pour produire un énorme panache de poussière. Celle-ci est resté en suspension un certain temps dans l’air. Avant de retomber doucement se déposer à la surface du sol. Les scientifiques ont aussi retrouvé des fragments d’une taille importante. Et un morceau de plus de 500 kg a même été détecté au fond du lac Tcherbarkoul situé sous la trajectoire de la comète.
De mystérieux cristaux sphériques et hexagonaux
La neige qui est tombée peu de temps après la chute du météore de Tcheliabinsk a piégé de minuscules grains de poussière.
Sous l’oculaire du microscope optique, les chercheurs ont observé de minuscules structures de quelques micromètres seulement. Grâce à l’utilisation du microscope électronique, ils en ont trouvé beaucoup plus et ont surtout pu réaliser des observations plus détaillées.
Les structures cristallines sont de deux formes ! Les premiers cristaux sont des coquilles parfaitement sphériques. Et les secondes des prismes à base hexagonale.
Afin de découvrir la structure plus intime des cristaux, les scientifiques se sont servis de la puissance des rayons X. Ils ont découvert qu’ils étaient constitués de graphite. C’est-à-dire de feuillet d’atomes de carbone de l’épaisseur d’un atome empilés les uns sur les autres. Mais le plus étonnant dans ces cristaux reste sans doute leur cœur ! Il pourrait être constitué d’un buckminsterfullerène ou de polyhexacyclooctadécane. La première molécule est constituée de 60 atomes de carbone et ressemble à une sorte de cage sphérique. Tandis que la seconde contient des atomes de carbone et d’hydrogène.
Ces cristaux auraient peut-être été façonnés lors de la fragmentation de la météorite lors de sa rentrée atmosphérique. Ceci en raison des hautes pressions et la température élevée.
Pour le moment, le mécanisme de formation de ces cristaux reste incertain. Les chercheurs aimeraient continuer leurs investigations pour analyser d’autres poussières de météorites. Et vérifier si les cristaux de la météorite de Tcheliabinsk sont uniques ou au contraire répandus.

Осенью этого года НАСА и Роскосмос собираются возобновить совместные полеты на МКС.

The United States and Russia said Friday they would renew flights together to the International Space Station, preserving one of the last areas of cooperation amid Western attempts to isolate Moscow over the invasion of Ukraine.
"To ensure continued safe operations of the International Space Station, protect the lives of astronauts and ensure continuous US presence in space, NASA will resume integrated crews on US crew spacecraft and the Russian Soyuz," the US space agency said in a statement.
NASA said that astronaut Frank Rubio would fly with two Russian cosmonauts on a Soyuz rocket scheduled to launch on September 21 from Kazakhstan, with another astronaut, Loral O'Hara, taking another mission in early 2023. n a first, Russian cosmonauts will join NASA astronauts on SpaceX's new Crew-5 which will launch in September from Florida with a Japanese astronaut also on the mission. Another joint mission on the SpaceX Crew-6 will fly out in early 2023, NASA said.
The move comes despite the European Space Agency earlier this week terminating its relationship with Russia on a mission to put a rover on Mars, infuriating Russian space chief Dmitry Rogozin who banned cosmonauts on the ISS from using a European-made robotic arm. But hours before NASA's announcement, President Vladimir Putin dismissed Rogozin, a firebrand nationalist who once quipped that US astronauts should get to the space station on trampolines rather than Russian rockets. Roscosmos, the Russian space agency, said the agreement with NASA was in the interests of both countries and "will promote cooperation" on space.
"The agreement seeks to guarantee that in the event of an emergency caused by the cancellation or major delay in a Russian or American space launch, at least one Roscomos cosmonaut and one NASA astronaut will be present to service the Russian and American sections respectively," it said.
NASA said that the ISS was set up for joint participation by the United States and Russia along with Europe, Japan and Canada.
"The station was designed to be interdependent and relies on contributions from each space agency to function. No one agency has the capability to function independent of the others," NASA said.
'Dear friends' in space
Soyuz rockets were the only way to reach the space station until SpaceX, run by the billionaire Elon Musk, debuted a capsule in 2020. The last NASA astronaut to take a Soyuz to the station was NASA astronaut Mark Vande Hei in 2021. He returned to Earth in March this year alongside Russian cosmonauts, also on a Soyuz. Speaking to reporters afterward, Vande Hei said that the cosmonauts remained his "very dear friends" despite their nations' tense relationship.
"We supported each other throughout everything," he said. "And I never had any concerns about my ability to continue working with them."
The United States has imposed sweeping sanctions on Russia after Putin on February 24 invaded Ukraine. The sanctions, which include tough restrictions on financial interactions, have led to an exodus of leading US brands from Russia including Starbucks and McDonald's. But the International Space Station is unique. It was launched in 1998 at a time of hope for US-Russia cooperation following their Space Race competition during the Cold War.
The ISS is expected to wind down in the next decade.

Физики ДВО РАН и СО РАН разработали новый поглотитель света для солнечных элементов и фотодетекторов на основе черного кремния, покрытого дополнительным слоем силицида магния. Материал поглощает более 95% света в диапазоне длин волн 200-1800 нм.

Scientists at the Institute of Automation and Control Processes in Russia have developed a novel kind of black silicon that they say has a higher near-infrared (NIR) light absorption and is better adjusted to absorb solar irradiance in the 1100-1800 nm range.
"We simply added one another absorbing layer atop black silicon, which replicates its morphology to some extent," the research's corresponding author, Alexander Shevlyagin, told pv magazine. "We have already demonstrated solar cell operation of a silicon-silicide heterojunction without surface texturing in our previous work."
In the paper "Mg₂Si is the new black: Introducing a black silicide with >95% average absorption at 200-1800 nm wavelengths," published in Applied Surface Science, the Russian research team explained that the new absorber layer was made of magnesium silicide (Mg₂Si), which is an inorganic compound consisting of magnesium and silicon with an energy bandgap 1.5 eV. "Mg₂Si is a Si-compatible optical material with superior absorbance from the ultraviolet (UV) to NIR regions compared to bare silicon," it explained. "It has already demonstrated photovoltaic perspectives as homo-/heterojunction photodetectors and solar cells."
The researchers implemented what they called the "silicidation" of the black silicon through a low temperature and scalable process that doesn't require an ultra-high vacuum and can be conducted by thermal evaporation and magnetron sputtering. They fabricated the black silicon substrate for black magnesium silicide preparation via reactive ion etching of a crystalline silicon wafer and then used used vacuum evaporation to cover the substrate surface with the Mg₂Si layer.
"The reflectance spectrum of the Mg₂Si covered b-Si nanocones demonstrates strong NIR antireflection performance when compared to starting b-Si surface," the academics emphasized. "Our measurements confirm averaged reflection in the 200-1800 nm spectral range of 3.7% from black magnesium silicide surface, which is 5 times lower with respect to 17.6% of the bare black silicon."
According to them, the material's improved light trapping properties should be attributed to the complex hierarchical nanocone-nanoflake structure realized in the new compound, which resulted in the marked increase of both NIR antireflection and absorption properties. "NIR photons after being back-scattered within b-Si nanocones are effectively absorbed by Mg₂Si possessing much higher intrinsic absorption coefficient over the wide spectral range," they further explained.
The group called the new wide-band black material "black silicide" and said it may also be used for NIR optical absorbers and highly sensitive NIR devices. "The results obtained propose a simple technology to further enhanthe photoelectric conversion efficiency of the silicon-silicide tandem solar cells using a black silicon instead of pyramid-like Si surface textures as a platform for silicidation with other environment-friendly and silicon compatible silicides," they concluded.

В 2023 года компания «Норникель» начнет финансировать научные исследования по оценке состояния водных биоресурсов и среды обитания рыб. Этим разработкам не хватает финансирования, и такая поддержка поможет не только российской, но и мировой науке в целом, считают эксперты. В дальнейшем компания планирует ежегодно выпускать мальков различных ценных видов рыб в сибирские реки.

One of the largest producers of nickel, copper and other metals in the world, Russian Norilsk Nickel will work to improve biodiversity in Siberian rivers.
Starting from 2023 the company will start to finance scientific research on the assessment of the state of aquatic bioresources and fish habitat. These scientific developments lack funding, and such support will create a benefit not only for Russian science, but also world science as a whole, experts believe. Later on, the company plans to annually release fry of different fish species into Siberian rivers, including one of the region's largest rivers, the Yenisei.
As the producer specified, Nornickel supports biodiversity and is engaged in multiplying rare and valuable biological species in all regions where the company operates.
"Tens of millions of rubles are allocated annually to replenish fish diversity. In the last five years alone, thanks to the company, the Yenisei River has been replenished by more than 1.2 million Siberian sturgeon fry. "Nornickel also replenishes stocks of grayling, char and other species under an extensive stocking program initiated in accordance with scientific recommendations. This program is part of the company's efforts to reduce the negative impact on nature," Nornickel said in a statement.
Nornickel, together with scientists from the Siberian Division of the Russian Academy of Sciences, is conducting a large-scale baseline study of biodiversity in the regions where the company operates - in Siberia and the Arctic - in 2022. This research includes soil studies, ornithology, zoology, and hydrology, among others. In addition, the Big Norilsk Expedition has been working in Taimyr for the third year now to study the nature around the main water bodies of the region.
Earlier in 2020, Norilsk Nickel Finland's Harjavalta division took on the conservation of freshwater mussels in the Kokemäenjoki River in western Finland.
As a result of surveys conducted in the summer of 2020, scientists found that mussel numbers were recovering.
The results showed a very good recovery of three of the four mussel species. Anodonta anatina, for example, recovered 229 percent in six years. At the same time, Unio crassus recovered by 4 percent. Meanwhile, examining the river bottom, it was noted that in some areas the number of mussels was unchanged, while in other areas of the river bottom it increased significantly.
The goal of the program is to revive freshwater mussel populations both in Finland and around the world.

Российские и норвежские ученые изучили, как влияет озонирование на растворенные в воде органические вещества в замкнутой аквасистеме, например, на рыбной ферме. Это поможет подобрать оптимальные методы очистки для конкретной системы.

Published in the Science of the Total Environment journal, the study highlights the effectiveness and limitations of ozone treatment and invites further research into developing water-dependent purification methods, suggesting a more scientifically grounded approach to that aspect of fish farming.
"While ozonation is widely used at fish farms to purify water from organic compounds, no one has undertaken a detailed analysis of how this purification technique affects water quality and the levels of the various kinds of organic molecules," study co-author senior research scientist Alexander Zherebker of Skoltech commented. "Using ultrahigh-resolution mass spectrometry we pinpointed the compounds susceptible to ozone treatment and their decomposition products. So, having these results fish farmers can draw conclusions as to whether ozone treatment is well-suited for their local water. At the same time scientists can follow up with complementary studies into other purification techniques. Ultimately, this can guide smarter business decisions based on modern science."
The organic matter that the researchers investigated enters the RAS tank from the natural water body that acts as the farm’s external supply source. The team repeatedly tested how the organic compound content and quality changed as time passed and as eventually ozone treatment was performed.
"We see what kind of organics is coming in from the outside. Although it soon mixes with fish feed traces and waste products, we can clearly see the water starts out rich in humic-like and unsaturated CHO compounds. This stuff is associated with water blooming, changes in microelement transfer and microorganism activity; and obviously, it upsets fish. After ozonation the levels of these compounds drop and instead, we see greater concentrations of new fulvic-like and saturated compounds. Those are the decomposition products. They are more inert and therefore fish-friendly," Zherebker explained.
Some compounds proved tolerant to ozonation, though - they may actually react with ozone but at higher doses. One caveat is that too much ozone will alter oxygen concentration and unavoidably impact fish health - they are only happy with natural oxygen concentration.
What enabled such a detailed analysis of dissolved organic matter was a highly sophisticated technique called Fourier transform ion cyclotron resonance mass spectrometry. It detects the presence and relative concentrations of various chemical species in a sample, without knowing exactly what you are looking for in advance - so-called untargeted analysis.
Skoltech researchers, along with their Russian and Norwegian colleagues, ran mass spectrometry analysis and data treatment as part of the study. The Russian-Norwegian partnership was facilitated by the Transnational Access programme under the European Commission’s Horizon Europe funding programme.
"Our algorithm can now be applied to methods other than ozonation and to other systems to evaluate the effectiveness of different water purification techniques and select the best set of tools for a company’s individual needs," study co-author Professor Evgeny Nikolaev concluded; he heads Skoltech’s Mass Spectrometry Laboratory, where the research was conducted.

Уральские ученые синтезировали 34 новых соединения платины с подтвержденной противомикробной активностью, которые в дальнейшем могут использоваться в фармацевтике. Синтез проводился с использованием хлорида натрия, что позволило избежать одного из недостатков платиновых соединений - плохой растворимости.

Scientists at South Ural State University have successfully created 34 new platinum compounds with confirmed antimicrobial activity. These compounds can be used in pharmaceuticals in the future. The results of their research have been published in the Journal of Coordination Chemistry.
Platinum compounds are catalysts that speed up reactions and make chemical processes more efficient. In addition, platinum compounds exhibit biological activity, which allows them to be used as antimicrobial and anticancer medications. A team of SUSU scientists synthesized the new compounds using sodium chloride, which significantly increased their efficiency and solubility.
"Molecular platinum compounds are currently receiving a great deal of attention. But one of the drawbacks of these compounds is their poor solubility. Since we are talking about pharmaceuticals, it is good when they are soluble in water or other solvents. Therefore, we began working with ionic compounds using sodium chloride. We took various phosphorus cations - phosphonium salts - as the basis for the cations. They are stable, accessible, and are excellent sources of cations. We took platinum derivatives as anions. At the same time, the phosphorus compounds themselves are also biologically active. As a result, both cation and anion are biologically active," explains one of the authors of the study Olga Sharutina, Head of the SUSU Department of Applied and Theoretical Chemistry.
The synthesis method developed by SUSU chemists uses readily-available solvents, making it fairly easy to synthesize such compounds at minimal cost.
The SUSU School of Medical Biology's Laboratory of Computational Modelling of Drugs has developed a computer algorithm for the study of chemical compounds that can then become drugs. This algorithm showed the high antimicrobial effectiveness of all 34 new platinum compounds.
At the next stage, compounds will be tested on living organisms. An agreement has already been reached on joint research with South Ural State Medical University and colleagues from India.
South Ural State University is a university of digital transformations, where innovative research is conducted in most of the priority fields of science and technology development. In accordance with the strategy of scientific and technological development of Russia, the university is focused on promotion of big scientific interdisciplinary projects in the field of digital industry, materials science, and ecology. In 2021 SUSU became the winner in the competition under the Priority 2030 program. The university acts as a regional project office of the World-class Ural Interregional Research and Education Centre (UIREC).

предыдущий месяц

1998-2022

следующий месяц