Latest news with #EhimeUniversity
Asahi Shimbun
4 days ago
- Science
- Asahi Shimbun
Paper with ‘timer feature' allows erasing for short period of time
A writing and erasure test conducted on this sheet of paper coated with a special solution shows that ballpoint pen ink can be erased from its surface when a rubber eraser is used immediately after the ink is applied. (Provided by the Paper Industry Innovation Center of Ehime University) SHIKOKU-CHUO, Ehime Prefecture--A flash of inspiration struck professor Hiromi Uchimura about eight years ago as he looked at a popular erasable pen. "Paper equipped with a timer feature could be fun,' Uchimura, 64, said he thought at the time. That idea led to Uchimura's university research center here developing a new paper that allows letters written on it in ballpoint pen to remain erasable for a certain time. Ballpoint pens that can be erased are already readily available in the market. But this paper variety, which was registered under a patent in February, is unprecedented in that letters written on it with a ballpoint pen become indelible after a predetermined length of time. Paper of the variety therefore allows slips of the pen to be corrected on the spot but is proof against any later falsifications, said officials of the Paper Industry Innovation Center of Ehime University (PIICE), which is based here. INSPIRED BY HIT PRODUCT The idea by Uchimura, who is PIICE's director and distinguished professor of papermaking technology, was triggered by ballpoint pen products of the 'Frixion' series that had been released by Pilot Corp., a stationery giant. Letters written with a Frixion pen disappear when they are rubbed with a special rubber eraser, which makes the ink transparent under frictional heat. Frixion became an immediate, global smash hit. But the erasable ballpoint pen products of the series have one shortcoming: anything written with them can be doctored easily, so they have been banned from use for official documents. Uchimura wanted to overcome that drawback of permanent erasability. He thought a paper product with a timer feature, which would allow letters to be erasable for a certain time but make them indelible when that time limit is over, would be a convenient invention. Ballpoint pen ink is made up, among other things, of a pigment, a fixing agent and a liquid solvent. When the ink is applied on paper, the solvent sinks into the paper or evaporates, thereby causing the ink to dry, and the ink ends up fixed on the paper as the fixing agent binds with the pigment. Uchimura sought to slow the process whereby the solvent in the ink soaks into the paper. He decided to add fine structures on the paper surface to suppress ink permeation. For that purpose, he chose a material called cellulose nanofiber (CNF), which is made by splitting vegetable fiber into extremely fine fluffs. CNF is characterized by its light weight and high strength. Uchimura attempted to apply a thin coating of CNF solution to the surface of paper to suppress the permeation of ink while at the same time keeping the paper's surface texture largely intact. Paper surfaces have slight ruggedness due to the presence of fibers. When the coating was too thin, it failed to cover the bulges of fibers, which ended up with areas where letters were indelible. When the coating was too thick, on the contrary, that made the surface too smooth to retain the typical texture of paper. Uchimura fine-tuned the process to strike the right balance. MAKING WHAT DOESN'T EXIST YET A test conducted on prototype paper showed that ink could be removed completely from the surface when a rubber eraser was used immediately after the ink was applied on the paper, but stayed partially on the surface after three hours. The ink could seldom be removed when the eraser was used after 24 hours. Subsequent improvements have allowed free adjustment of the threshold time after which the ink became indelible, such as at six hours or 24 hours. PIICE is currently working jointly with a papermaker and a stationery manufacturer to develop products that use this paper variety. The feature that allows letters to remain erasable until a certain time elapses but makes them indelible when that time limit is over could allow the use of the paper variety in important documents, such as in papers to be submitted to government offices and in written agreements. Any slips of the pen could be corrected on the spot, during document preparation, without having to see smudges, for example, with the use of whiteout. 'Our development work has been motivated by a desire to make what doesn't exist yet in this world,' Uchimura said. 'I hope a (prospective) release of products from this 'papermaking city' of Shikoku-Chuo (which is home to many papermakers) to markets both in Japan and abroad will serve as a catalyst for (this area's) regional revitalization.'
Hans India
4 days ago
- Science
- Hans India
JWST uncovers new kind of black holes linking classical quasars and 'Little Red Dots'
Astronomers have identified a previously unseen class of supermassive black holes in the early universe by combining Subaru Telescope data with follow-up observations from the James Webb Space Telescope (JWST). These dust-enshrouded quasars, dating to within the first billion years after the Big Bang, bridge the gap between well-known, brightly shining quasars and the faint 'Little Red Dots' JWST first spotted in late 2022. For over a decade, ground-based surveys with Subaru flagged galaxies whose light signatures hinted at more than just star formation, but technical limits prevented a definitive identification. By re-examining 13 of these candidates using JWST's sensitive infrared spectrograph, an international team detected the telltale broad emission lines and high-velocity gas flows that confirm active galactic nuclei powered by supermassive black holes cloaked in heavy dust. Of those 13 galaxies, nine revealed these hidden quasars, whose intrinsic brightness rivals that of classical quasars but whose optical light is heavily reddened by surrounding dust—mirroring the characteristics of the 'Little Red Dots.' Lead author Yoshiki Matsuoka of Ehime University remarked, 'We were surprised to find that obscured quasars are so abundant in the early universe,' suggesting that many young black holes have eluded detection in previous surveys. Independent expert Jorryt Matthee of IST Austria, who was not involved in the study, praised the robustness of the spectral data and noted that this new population likely represents the 'missing link' between the rare, brilliant quasars and the smaller, dimmer red dots. As more of these objects are confirmed, astronomers will be able to estimate the masses of their black holes and host galaxies, offering fresh insights into how the earliest galactic giants grew. Building on these promising results, Matsuoka's team plans to use JWST to study roughly 30 more Subaru-selected targets. By mapping the environments and gas dynamics around these hidden quasars, researchers hope to unravel the origins of the Little Red Dots and refine our understanding of black-hole evolution at cosmic dawn.
