dNdx u quark

Clear[ub1, un1, un2, ud1, up];

ub1[M_] := uab1*(M^ubb1);
uab1 = 2.96;
ubb1 = 0.0506;


un1[M_] := ua1n1*(M^ub1n1) + ua2n1*(M^ub2n1);

ua1n1 = 1.90;
ub1n1 = 0.0172;
ua2n1 = 2.92;
ub2n1 = -0.351;

un2[M_] := ua1n2*(M^ub1n2) + ua2n2*(M^ub2n2);
ua1n2 = 0.0587;
ub1n2 = 0.146;
ua2n2 = 0.848;
ub2n2 = -0.145;


ud1[M_] := ua1d1*(M^ub1d1) + ua2d1*(M^ub2d1);
ua1d1 = 0.317;
ub1d1 = -0.0300;
ua2d1 = 0.403;
ub2d1 = -0.351;

up[M_] := uap*(M^ubp);
uap = 4.74;
ubp = 0.839;


Clear[logu, utotal, x];
logu[M_, x_] = 0.00093*(Log[up[M]*(1.0 - x)])*(x^0.5)*(x^2 - 2*x + 2);

utotal[M_, x_] := 5.58*Exp[-ub1[M]*(x^un1[M]) - (0.315/(x^ud1[M])) - 5.5*(x^un2[M])] + logu[M, x];

Plot[utotal[5000,x],{x,0.0001,1.03},PlotRange->All]