Germany has found a source of perovskite for solar panels in an unusual place: bullets from the 17th century

Solar energy is, with the permission of wind energy, the renewable energy that has stood out the most and best in the energy transition on a global scale. There are already solar parks everywhere: from fields that They fill the emptied Spain to deserts passing through the tibetan plateau and also in high seas either in lakes. And although the most common technology is crystalline silicon, perovskite is the great promise. There is a compelling reason to bet on perovskite: a record efficiency certified in a laboratory. up to 26%. However, a large-scale deployment of perovskite solar cells requires a large-scale, sustainable supply of high-purity lead iodide. We have come across lead: a toxic element whose mining is not exactly sustainable. On the not-so-good side, recycling it to the required purity levels is a technical challenge that a German research team at the Helmholtz Institute in Erlangen-Nuremberg has just solved. And in what way: have achieved converting 17th century musket balls into high-performance solar cells. The idea. It consists of a process of upcycling (upcycling) in two stages: first a non-aqueous electrochemical route and then purification through the crystallization of single crystals, quite different from traditional methods based on strong acids and large volumes of water. To demonstrate the robustness of their method, the team used lead bullets from the 16th and 17th centuries as raw material, a truly complicated material in that it contains carbon residues, metallic inclusions and oxidation patina. If the process can clean up this type of historical residue, it can handle virtually anything you throw at it (obviously any lead residue). Recycling bullets into solar cells transforms lead waste into a clean energy source. Why is it important. Perovskite solar cells require extraordinarily pure lead iodide, and achieving that level of purity from contaminated waste was until now a challenge without a practical solution that this research has solved: the team manufactured solar cells with their recycled material and obtained 21% efficiency, practically identical to the 22% of devices manufactured from industrial synthesis. Beyond the technical result, the process solves two problems at the same time: it offers a way to supply the enormous demand for lead iodide that will be generated by the take-off of perovskite solar cells without resorting to new mining and at the same time eliminates a toxic pollutant whose current management is expensive and environmentally problematic. Context. As we mentioned above, lead is an abundant waste: it comes from used car batteries, electronic scrap, construction materials or ammunition, among others. Lead recycling is dominated by car batteries, which have very high recovery rates in developed countries. The problem is in the rest: In 2018, only 48% of the world’s residual lead at the end of its useful life was recovered and in more dispersed flows such as electronics or construction, the recovery is even lower. Conventional recycling returns metallurgical-grade lead, useful for batteries and alloys, but far from what the solar industry requires. In addition, they are slow processes that generate toxic gases such as nitrogen oxides and large quantities of contaminated wastewater, up to 70 liters per kilogram of lead iodide produced. Traditional high-temperature purification methods are expensive and complex. More robust, adaptable and cleaner extraction and purification methods are needed for perovskite technology to truly scale. How they do it. The bullets are cleaned with dilute nitric acid, melted and molded into rods that act as electrodes in an electrochemical cell with acetonitrile and dissolved iodine. When current is applied, lead reacts directly with iodine and precipitates as lead iodide with 94% efficiency. Doing it this way, in a non-aqueous medium, is a deliberate decision to avoid introducing impurities that would accelerate the degradation of the perovskite. The resulting lead iodide still contains metallic impurities, so it is not suitable for solar cells. That is why it is subjected to a second purification stage through crystallization at a controlled temperature for about 70 hours. The process is exceptionally selective: as the crystal grows, it expels contaminating metals such as silver or copper, raising the purity of the material to levels comparable to or even higher than the highest quality commercial standard. Yes, but. The process works and the results are solid, but scale matters: at the laboratory level, productivity is just 0.05 grams per hour and each purification cycle lasts about 70 hours. The leap to an industrial scale requires solving the recovery of organic solvents, controlling the passivation of the electrodes and substantially improving the productivity of the process. The research team does not hide it: the chemistry is proven, but the distance from the laboratory to a real production plant is long and will determine whether we end up seeing perovskite panels made with recycled lead or if this remains like a shiny piece of paper in a drawer. In Xataka | Germany has had a crazy idea to solve one of the problems of renewables: covering a lake with solar panels In Xataka | 800 meters deep in a 175 million year old rock: Germany’s solution to nuclear waste Cover | By Branch and Soren H

an Arabic document from the 17th century has confirmed its existence

If we think about characters and civilizations in African history, most of us think of the pharaohs and pyramids of Ancient Egypt and little else. However, there is much more and you don’t have to go far from that enormous continent: just to the south, following the river inland, there were powerful kingdoms with their own kings, their own cities and their own cathedrals (yes, I said cathedral). One of those kingdoms was called Makuria, and its capital was Old Dongola, a great city on the banks of the Nile that for almost a thousand years was a center of power, commerce and culture. Curiously, while Europe was living through the Middle Ages, Dongola was a prosperous Christian city that even stood up to the Arab armies that conquered North Africa. Over time it declined, became Islamized and was almost forgotten, buried under the desert. The history of the region Nubia It is almost a documentary silence. It’s not that nothing happened: it’s that almost nothing was written or what was left had not been excavated. In that darkness, a small fragment of Arabic paper recovered in a garbage dump in ancient Dongola (the north of present-day Sudan) has just marked a before and after. The discovery. The document measures just 10 × 9 centimeters, it was found in a garbage dump inside Building A.1 of the Old Dongola citadel (what has been popularly known there for centuries as the “King’s House”) and it is an administrative order issued in the name of King Qashqash. The king orders a subordinate named Khiḍr to arrange an exchange of sheep with their offspring, cotton cloth, and a headdress between several individuals. The text was written by the scribe Hamad and the research team behind the paper considers that it is probably the response to a previous letter, suggesting that there was an active epistolary network around the court. It is, simply, the king working on his task of administering, managing assets and relationships within his network of power. The first face of the King’s order. M. Rekłajtis/PCMA in Barański et al. 2026 Why is it important. The relevance of the discovery has several levels, but the most direct and immediate is to confirm the historical existence of Qashqash, of which there was previously only evidence through oral tradition, including fragments of the Kitāb al-Ṭabaqāt of Wad Ḍayfallāh. This book compiled in 1700 compiles the biographies of the most important saints and religious teachers of the Sudan, based on stories that had been transmitted orally from generation to generation. Beyond that confirmation, the discovery sheds some light on what the “Dark Ages” of Nubia were like. For centuries the image left by Leo Africanus in the 16th century predominated, describing the king of Nubia as a monarch perpetually at war. This document demonstrates the opposite: the region was politically active and its king was not on the battlefield, but rather involved in the daily management of goods and networks of reciprocal exchange, which was the central mechanism of political power in precolonial Sudan. Context. Old Dongola was the capital for centuries of the Christian kingdom of Makuriaone of the most powerful medieval African kingdoms in the Nile Valley. In the mid-14th century it ceased to be so, and the city progressively contracted until it was reduced to its citadel and its immediate surroundings. What followed is the period that historians call the Sudanese “Dark Ages”: three centuries in which Dongola was caught at a geopolitical crossroads: with pressure from the north by Ottoman Egypt, from the south by the Funj sultanate, and meanwhile its society was Islamized. It was in that delicate context that Qashqash probably reigned between the second half of the 16th century and the first years of the 17th century. one of the first rulers of that dark period that has been able to be verified. How have they done it. The PCMA research team at the University of Warsaw have combined three independent avenues to date and contextualize the document: with numismatics using Ottoman silver coins from the same stratum, radiocarbon of organic matter from the garbage dump, and cross-literary genealogy, combining the Kitāb al-Ṭabaqāt and the account of the traveler Evliya Çelebi, the documented descendants of Qashqash. The convergence of the roads has made it possible to reconstruct the limits of when his reign was. Qashqash is just the tip of the iceberg. The document is also a linguistic testimony of the first order: written in Arabic, it has grammatical irregularities and colloquial spellings that show that although it was not fully established, it was already the language used by the chancellery. In short: evidence of the gradual Arabization of Nubia, which was adopted and adapted. Another interesting point is that archaeological evidence and local oral memory confirm each other. Building A.1 has been called the “King’s House” by the inhabitants of Dongola for centuries and the descendants of Qashqash continue to live nearby. Finding the royal order precisely there is no coincidence: it is archeology validating what the community had remembered for generations. In fact, the collaboration between the research team and those who live there has been close, something they consider essential for a correct interpretation. Shedding light on the dark ages. The Qashqash order is only the first published result of a much larger corpus as the project has recovered approximately fifty Arabic paper documents in Old Dongola, including letters, legal and administrative texts, and written amulets. The first analysis points to communication networks that connected religious, administrative elites and possibly nomadic leaders of the region. A comprehensive and in-depth analysis of the set will shed some light on the political, legal and social history of pre-colonial Nubia. In Xataka | A cargo sunk in a Swiss lake 2,000 years ago confirms it: the Roman legions did not deprive themselves of anything In Xataka | A treasure hunter looted a shipwreck, did not reveal where he had kept the treasure and spent 10 years … Read more

In the 17th century there was a food that was considered deadly for the rich, but did not kill the poorest: the tomato.

Today it is almost impossible to imagine Mediterranean cuisine without tomatoes, a food highly valued by its nutritional benefits and their antioxidant propertiesanti-cancer and how preventative for aging cellular. However, its integration into the European diet was a slow process full of obstacles, marked by a phenomenon that stigmatized it for centuries, calling it a poisonous food that could lead to cause death, especially if you were rich. Curiously, the poor were immune to its poison. The tomato was deadly for the rich The history of the tomato hides a phenomenon that defied the logic of the time, as it seemed to act as a selective executioner capable of distinguishing the social status of those who ate it. While the peasants and the popular classes They consumed it without suffering harm In some cases, rich aristocrats and wealthy merchants became seriously ill and even died after ingesting it, which consolidated the belief that it was a poisonous and cursed fruit. However, the key to this medical mystery lies not in the biological composition of the tomato, but in the chemistry of the utensils used by rich Europeans when serving and preparing this food. The upper classes of the 18th century had the custom of serving their banquets in pewter tablewarea metallic alloy highly appreciated for its shine and similarity to silver, composed mainly of tin and copper, but with a high lead content. Unlike the rich, the humble classes could not afford these luxuries and ate on simple plates made of wood, clay or coarse ceramics, materials that were chemically inert to food. The problem was that, when the natural acidity of the tomato came into contact with the surface of the pewter plates, their interaction caused a chemical reaction that leached lead from the alloyreleasing this heavy metal directly into the food. As a result, the aristocrats suffered lead poisoning (lead poisoning), whose symptoms were erroneously attributed to the toxicity of the tomatoes and not to the dish in which it was served, granting him tomato the nickname “poison apple” for more than 200 years. Bad botanical companies The rejection of the tomato in Europe in the 17th and 18th centuries was not only due to the wealthy victims that this evil fruit claimed, but was supported by the botanical science of the time, which classified it under a family of some plants with a bad reputation: nightshades. Naturalists identify the tomato as a member of the Solanaceae, the same group to which plants belong. famous for their toxicity such as nightshade, henbane or mandrake. This botanical association was enough for doctors and scholars to assume that the new fruit native to the Americas shared the deadly properties of its distant relatives. This botanical classification reinforced the irrational fear of the plant, linking it not only with the poison that was clearly killing the richest, but with spiritual and moral dangers typical of the time. The mandrake, in particular, was strongly associated with witchcraft and rituals dark due to its narcotic effects and the anthropomorphic form of its roots. By placing the tomato in this same biological bag, all the negative connotations and superstitions that surrounded the plants used in the dark arts were transferred to it. As and as they pointed out in National Geographicthe herbalist John Gerard was one of those responsible for fixing this negative image in the collective mind, leaving in writing in his work Herball of 1597 a devastating sentence. Gerard described the plant as producing “corrupt and poisonous fruits”, a statement that, coming from an authority on the subject, cemented the terror of the tomato in Britain and its colonies for centuries. Although in Spain and Italy the tomato began to be accepted earlier due to the influence of customs brought from Americain northern Europe the shadow of suspicion lasted much longer. It was necessary for modern chemistry to explain the pewter reaction and for botany to refine its classifications so that the tomato could finally clear its name and occupy the place it today has on our tables, no matter if you are rich or poor. In Xataka | They are millionaires, but they eat like children. Warren Buffett and Mark Zuckerberg share a passion for junk food Image | Nano Banana, Unsplash (Wanasanan Phonnaun)

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