Help appreciated with identifying Moscow maker's marks, plz.

[Atlas]

So, help would be appreciated with identifying the following Moscow (1908-1917) maker's marks if you please.


The object is this (pics down below) Cloisonne-enamel vodka-beaker (5.25cm high / 54.90gr in weight), gilt-inside.


Regards,
- Atlas -

[Atlas]

So I guess the maker's marks remain a mystery?
- Atlas -

[Qrt.S]

Patience my good man, patience. Sometimes it may take a year or two before you get an answer....

[Mart]

So I guess the maker's marks remain a mystery?
- Atlas -

Hello! It is difficult to correctly identify the letters. Perhaps "ДН". The master with such a brand worked in those years, but is still unknown to me.

[AG2012]

If maker`s mark is upside down could it be ян ?

[Mart]

I've already checked "ЯН" (аnd many other combinations).I have not met such a brand.
With separate letters so far I have only met "ДН".