Science desk
< November 18	<< Oct \| November \| Dec >>	November 20 >

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is a transcluded archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

November 19[edit]

Green leaves in winter[edit]

I've noticed some deciduous trees retain several green leaves in winter (by November at least, like so). Why is that? 212.180.235.46 (talk) 15:36, 19 November 2022 (UTC)[reply]

It doesn't look to me like they've retained much of anything. Like chemistry, biological process (which are built on chemistry) rarely go to 100% completion, or at least not in a timely manner. 99% completion is pretty great. --OuroborosCobra (talk) 16:29, 19 November 2022 (UTC)[reply]

Since when is November part of winter? Even ignoring the Northern Hemisphere-centrism, neither the meteorological nor the astronomical definition of winter stretches that far. --User:Khajidha (talk) (contributions) 17:13, 19 November 2022 (UTC)[reply]

At 1st I thought this was a color question, so genetics, but the image and discussion makes it seem this is more of a wind question? Because the wind didn't blow it hard enough yet? 67.165.185.178 (talk) 17:17, 19 November 2022 (UTC).[reply]

See marcescence which is:-

...the withering and persistence of plant organs that normally are shed, and is a term most commonly applied to plant leaves. The underlying physiological mechanism is that trees transfer water and sap from the roots to the leaves through their vascular cells, but in some trees as autumn begins, the veins carrying the sap slowly close until a layer of cells called the abscission layer completely closes off the vein allowing the tree to rid itself of the leaf. Leaf marcescence is most often seen on juvenile plants and may disappear as the tree matures. It also may not affect the entire tree; sometimes leaves persist only on scattered branches.

Alansplodge (talk) 13:14, 21 November 2022 (UTC)[reply]

Weird, I can't tell the difference between marcescence and abscission for tree leaves that drop. 67.165.185.178 (talk) 02:58, 23 November 2022 (UTC).[reply]

The article Evergreen discusses broad-leaved trees that don't lose their leaves (like live oak, holly, southern Magnolia, etc.) There are sections which discuss why some of these trees don't lose their leaves. --Jayron 32 14:14, 21 November 2022 (UTC)[reply]

Machine printing on porcelain[edit]

In the history of art, it is said that the impact of the industrial revolution on porcelain manufacturing displaced artists from that profession because it allowed machines to print the designs directly on china, particularly in the early to mid-19th century. However, I cannot find anything about this technology or its inventors on Wikipedia. Can someone point me in the right direction? Thanks. Viriditas (talk) 20:07, 19 November 2022 (UTC)[reply]

The most relevant coverage on Wikipedia that I can find is Decalcomania. Think something similar to decals and transfer paper, or temporary tattoos popular with little children. The porcelain had an initial glazing. The pattern was printed on transfer paper, and then transferred to the surface of the porcelain item. Then, a transparent glaze was applied and the item was fired again. The technique goes back to about 1750. Take a look at Ceramics and Print, a book that has a chapter about the early history, starting on page 15. Cullen328 (talk) 20:27, 19 November 2022 (UTC)[reply]

Transfer printing also discusses the technique. Cullen328 (talk) 20:30, 19 November 2022 (UTC)[reply]

As I understand it, equipment that allowed machine printing directly on porcelain items without an intermediate transfer process was developed around the turn of the 20th century. Cullen328 (talk) 20:37, 19 November 2022 (UTC)[reply]

Thanks. The statement is made frequently in the art literature regarding French porcelain manufacturing in the 1850s. Just guessing, but there seems to be some secrecy surrounding the process, which is why there is little to nothing said about it. Viriditas (talk) 20:47, 19 November 2022 (UTC)[reply]

There is a technique using a soft rubber stamp, a bit like a flat soccer ball. The rubber is pressed against the inked flat pattern and then pressed against a plate, bowl or saucer. I've seen it done, but can't recall the correct name. Found it! "bat-ware", see Transfer_printing#Process. Martin of Sheffield (talk) 20:51, 19 November 2022 (UTC)[reply]

This is from German art historian Peter H. Feist (1987). "Renoir only spent four years as a porcelain painter. The industrial revolution made an immediate and irreversible impact on his life: a machine for printing pictures on china had been invented, which made him and many other porcelain painters redundant." The biographical article on Renoir says "the porcelain factory adopted mechanical reproduction processes in 1858" forcing him out of his chosen profession.

See also Théodore Duret (1910): "The decoration of porcelain [in the 1850s] had hitherto been done by hand, but now a machine was invented which rendered hand labour unnecessary. Porcelain painters were suddenly deprived of their means of livelihood." Viriditas (talk) 21:14, 19 November 2022 (UTC)[reply]

The "flat soccer ball" machine sounds more like pad printing. DMacks (talk) 21:28, 19 November 2022 (UTC)[reply]

Yamanaka-Method[edit]

Is there a detailed technical description of the method to abrogate adult stem cell differentiation? 2A02:908:424:9D60:1728:3390:1D6B:BA69 (talk) 21:04, 19 November 2022 (UTC)[reply]

Reference [17] in our article Induced pluripotent stem cell is the publication in which Yamanaka and his group describe their method for reprogramming human cells to become pluripotent. I have not read it and don't know if it is sufficiently detailed to allow replication. --Lambiam 05:42, 20 November 2022 (UTC)[reply]