Q Exactive

When treating polyatomics it is convenient to define an average molecular partition function, In = (lnQ)/N, for an assembly of N molecules. In the dilute vapor (ideal gas) this introduces no difficulty. There is no intermolecular interaction and In = (In Q)/N = ln(q) exactly (q is the microcanonical partition function). In the condensed phase, however, the Q s are no longer strictly factorable. Be that as it may, continuing, and assuming In = (In Q)/N, we are led to an approximate result which is superficially the same as Equation 5.10,... 

This equation has three types of solutions. First, there are the uniform solutions, tij=n, for which q = (fey — kb)n( 1 — n), as given by Eq. (20). Second, when q exactly equals the maximum flux permitted in the uniform density case, namely (kf — kb), the solutions are of the form... 

The reactance matrix K is ai Q. Exact solutions require the matrix to be of rank n0, implying n linearly independent null-vectors as solutions of the homogeneous equations ma = 0. Because this algebraic condition is not satisfied in general by approximate wave functions, a variational method is needed in order to specify in some sense an optimal approximate solution matrix a. 

Q Exactive Hybrid Quadrupole-Orbitrap mass spectrometer from... 

Analyze by direct infusion using a Q Exactive Hybrid Quadrupole-Orbitrap mass spectrometer (ThermoFisher Scientific). AH analyses are performed with resolving power set to 140,000, four microscans for 30 s. 

It means that the scattering (or diffraction) intensity and the autocorrelation function are reciprocal Fourier transforms similar to the reciprocal transforms of scattering amplitude F(q) and density p(r). It should be noted that in statistical physics one widely uses the density correlation function G(r) mentioned earlier (5.26) that is related to the structure factor S(q) exactly as the Paterson function is related to intensity of scattering 7(q). Below we prefer to use G(r). 

Figure 2.25 TransMIT s AP SMALDI source design for mass spectral imaging attached to Thermo Scientific Q Exactive instrumentation. Adapted with permission from Thermo Scientific.

The Orbitrap technology is the property of Thermo Fisher Scientific, which has now marketed two different product families with several variants. The Q Exactive instrument, as shown in Figure 2.25, is a bench-top Orbitrap analyzer with a 90° bend of the ion path to limit the footprint of the instrument. Its mass-resolving power is 140000 at m/z 200, and the accessible mass range is up to 6000 Da. 

Q-Exactive Orhitrap Full sacn MS acquisition mode (m/z 65-950)... 

Professor Q Exactly We don t know So we must simply make an assumption and let the solution to the system of equilibrium equations tell us whether our assumption is correct or not. ... 

Professor Q "Exactly right, Frank So, for our final answer, the friction force is 10.2 newtons, oriented on a 20-degree angle, down and to the left. 

Going back to our reconciliation problem, the objective function is the criterion Q (10.4.32). This particular function depends only on the x-subvector of z (10.1.29), and is quadratic in x. Hence in (10.4.64a), the development q up to the 2" degree equals Q exactly. But then, the problem (10.4.64) is no other than (10.4.64a) with (10.4.50). Hence the short-cut method according to Subsection 10.4.4 can be regarded as an SQP method tailored for the special case, with partitioned vector z and Jacobi matrix Dg = (B, A). 

The wavevector q of waves with a phase velocity uj/q exactly equal to the velocity Vp of the ridge is given by the condition ... 

Lin, Y. K. and Cai, G. Q., Exact solution for nonlinear systems under parametric and external white-noise excitations. Part II, to appear. 

High Mass Accuracy-Based Shotgun Lipidomics Currently, commercially available hybrid instruments (e.g., quadrupole-time-of-flight (Q-TOF) or Q-Exactive (i.e., quadrupole-Orbitrap) mass spectrometers) offer an improved duty cycle that increases the detection sensitivity and/or high mass resolution/accuracy [18, 19]. These instruments can thus be employed to quickly perform product-ion... 

In another development on measuring mitochondrial lipids. Bird et al. [72] employed LC-MS with a Q-Exactive mass spectrometer and operated at high-energy CID for extensive MS/MS analysis. They detected the species of prenolipid, sterol, sphingolipid, fatty acyl, CL, PC, lysoPC, PE, and PS classes in the study. 

---