anchor.diff:      end if 
     end subroutine concentration_field_cylindrical
   
  -  subroutine md_vel_flow_partial(particles, dt, ext_force)
  -    type(particle_system_t), intent(inout) :: particles
  -    double precision, intent(in) :: dt
  -    double precision, intent(in) :: ext_force(3)
  -
  -    integer :: k
  -
  -    call solvent%time_md_vel%tic()
  -    !$omp parallel do
  -    do k = 1, particles% Nmax
  -       if (particles% wall_flag(k) == 0) then
  -          particles% vel(:,k) = particles% vel(:,k) + &
  -               dt * ( particles% force(:,k) + particles% force_old(:,k) ) / 2 &
  -               + dt*ext_force
  -       else
  -         particles% wall_flag(k) = 0
  -       end if
  -    end do
  -    call solvent%time_md_vel%tac()
  -
  -  end subroutine md_vel_flow_partial
  -
  -  subroutine buffer_particles(particles,edges, bufferlength)
  +  subroutine buffer_particles(particles,edges)
        type(particle_system_t), intent(inout) :: particles
        double precision, intent(in) :: edges(3)
  -     integer, intent(in) :: bufferlength
     
        integer :: k, s
   
  
positive.code:      do k = 1, particles% Nmax
          s = particles% species(k)
          if (s <= 0) continue
          if ((particles% pos(1,k) > randomisation_length) .and. (particles% pos(1,k) < bufferlength)) then
             if (particles% pos(2,k) < edges(2)/2.d0) then
                bulk_change(s) = bulk_change(s) - 1
                particles% species(k) = 1
  
negative.code:   call h5md_write_dataset(timers_group, solvent%time_ct%name, solvent%time_ct%total)
    call h5md_write_dataset(timers_group, solvent%time_max_disp%name, solvent%time_max_disp%total)
    call h5md_write_dataset(timers_group, flag_timer%name, flag_timer%total)
    call h5md_write_dataset(timers_group, change_timer%name, change_timer%total)
    call h5md_write_dataset(timers_group, buffer_timer%name, buffer_timer%total)
    call h5md_write_dataset(timers_group, randomize_timer%name, randomize_timer%total)
    call h5md_write_dataset(timers_group, neigh%time_update%name, neigh%time_update%total)
    call h5md_write_dataset(timers_group, varia%name, varia%total)
    call h5md_write_dataset(timers_group, neigh%time_force%name, neigh%time_force%total)
  