Bruce Tai

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About Bruce Tai

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    https://sites.google.com/site/ntutailab/
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    Stradivari violins, hi-fi audio, music collection

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  1. We measured 7 European spruce and 7 European maple, Al is less than 10 ppm in all cases. Three repeats each.
  2. No worries. There are many experts reading these forums and they contact me privately regarding useful information and samples. This forum enabled me to connect with many makers and restorers over the past 15 years. This is the distinct advantage I have over many violin researchers, an extended circle of global experts giving me advice. When I come up with new ideas or hypotheses, this circle helps me filter out the impractical and the improbable. I am guided by centuries of combined violin making experience while not having made a violin myself. The expert makers are always learning new stuff
  3. From the link above: "Although Chenery (11) did not consider gymnosperms to be aluminum accumulators, Truman et al. (14) proposed that most Pinus species are facultative aluminum accumulators." Here is reference 14: Title-- Effect of varying solution ratios of Al to Ca and Mg on the uptake of phosphorus by Pinus radiata Summary:-- "Pinus radiata (D. Don) seedlings were grown in nutrient solutions in which phosphorus levels varied from deficient to adequate. In the first experiment, Al was substituted for Ca over the range 0 to 0.4 meq/l and P was applied at two low levels
  4. The attached file shows that the median concentration of Al in 23 wood chip samples. The median value is 14 ppm. These are very crude wood chips sold in bulk. Noticed the maximum values are often extraordinarily high, indicative of serious contamination. The conclusion of this study is that many commercial wood pellets sold in bulk have serious contamination issues. ef300884k.pdf
  5. In published papers we describe the funding sources and disclose any conflict of interest. My research is funded by Taiwanese taxpayers. The only private funding I had was from Chimei Museum to pay for the open access option. Thanks to Chimei everyone can read the paper for free.
  6. Fritz et al. did not show us which Strads were tested. That is totally understandable because we have to respect tthe owners and heed to their interests. Mutual respect is what moves things forward.
  7. Very often the restorer removed something, and did not record any details. Each time the knife goes, a flake comes off. Then they all go to a plastic bag. Who knows which flake is from which part? Did the owner give consent that the flake could be used for research 30 years later? Probably not. So let's not be too specific about the instrument and the exact location. What if this is violin is up for sale next month? We don't want to expose its repair record. We don't want to disturb the violin business with any research. Leave that to the appraisers, auctioneers, and dealers. Don't ask,
  8. Wood itself is about pH 4 or 4.5. Small amounts of alum is safe. Wood has its own pH buffering capacity. No one knows the real limit in the long-term stability. A We tested with iPhone earbud diaphragms. Thanks to precision manufacturing, their frequency response curves are extremely reproducible, measured on special testing equipment. Mastering engineers won't consider 2 dB bass boost inaudible. As you noted, it's too hard to measure small changes on wood, too much variability. Headphone diaphragms much more consistent. Our point was to show that 3000 ppm Al provides sufficient chemical
  9. The X-ray fluorescence imaging at SwissLight synchrotron shows that Al was diffusely distributed into wood cells. That had to be soluble Al. Aluminum silicates and aluminum oxides are common but insoluble. I don't know any other soluble aluminum salt sold at premodern apothecaries except for alums.
  10. I don't think discussions can be productive if incessant trolling is not controlled by the moderator. The original poster should have the right to ask the incessant troll to be locked out from making further posts in this thread. The internet troll, GeorgeH, is repeating the same message over and over again without any insight to add.
  11. I already presented the hypothesis that wood suppliers may have done the chemical treatments in my 2017 PNAS paper. GeorgeH is now using our older hypothesis to do the trolling, brilliant. Quoted from my PNAS paper: "Because violin plates are only a few millimeters thick, dimensional stability is an extremely important tonewood quality. Immersion of dried tonewood into liquids is likely to cause swelling damage and compromise dimensional stability, and is therefore generally avoided. Before the introduction of pressurization methods in the 1800s, extensive mineral penetration by soa
  12. Ignoring the troll.... It's plain silly to comment on the scope of the study before reading the whole paper, which has not been published yet. Patience is a virtue. Nagyvary had one Andrea Guarneri spruce and made some quick measurements. He thought the Al was added intentionally. Forty years later, our data are consistent with Nagyvary's original interpretation. That's called reproducibility. Patience is a virtue. The Guarneri family had a special preference for aluminum. Three out f three, completely independent samples. Grandfather and grandson. Neighbors did not add it. It's v
  13. I think it would be helpful to approach this question using a source-filter model. The source is the neck, strings, bow, the bridge, and the player. In singing it's the vocal cord. The filter is the body. In singing it's the vocal tract. The source-filter model assumes that the two work independently. This is probably a good approximation for the violin. Since the Baroque age, the source has changed a lot. But the filter remains similar. Bass bar is made bigger and the wood aged older. Some repairs and patches here and there. But these are minor changes. Even in the mod
  14. Can GeorgeH stop playing the parasitic game of distorting my messages? Can GeorgeH prove that the Strad and Guarneri violins he has heard are actually made by those masters, and offer statistical proof in his own defense? How many sigmas does GeorgeH plan to use to prove that he has even heard a Strad in his life? Is six sigma statistics enough to convince the rest of us? Show some courtesy for researchers who have done actual experiments on this topic, and let other people have a meaningful discussion without internet trolling. My collaborators have done ~4500 ICP-MS elemental measureme
  15. Which wood did you steam? We have learned that boiling spruce can promote cellulose rearrangement but boiling maple cannot. There are fundamental differences between softwood and hardwood. A topic that is underexplored. We are just beginning to explore.