Little Duet 4th

Final movement of a four part piece. Since I am not a string player I am especially interested in any advice regarding the notation, which hopefully is not too far off the mark.

The music flows nicely in sort of neobaroque fashion. Despite some good moments there are also questionable vertical dissonant clushes of independent lines which seem not to be coordinated properly. Try to improve the vertical sound of the polyphony - Hindemith would be a good choice to take an example from.

The bar 51 features impossible moment for cello: the interval C-F cannot be played unless of alternative tuning which you probably did not have in mind.

Most of the arcs should change on semiquavers (bar 2 for exampe) and not lasting a full bar.

1. Dynamics don't belong on top of the line.
2. Unrealistic bowings that, currently unmarked, use awkward bow directions for awkward dynamic shifts and string crossings. In general practice, never use slurs for strings as phrase markings.
3. Double stops are at time either incredibly difficult (i.e. cello measure 14), or impossible (i.e. cello measure 18 or 51). There's no hard and fast rule to learning how to write proper double stops. This will take research, best by learning the instruments.
4. No double bar on the last measure? No transitionary bars between sections? 
5. Occasional crossed voices (i.e. measure 22).

I see you making a musical arc... it needs to be refined. 
 

Thanks very much for your responses and critiques. Greatly appreciated!