Nuclear Spin Singlet Pulse Sequences for Multi-Molecule NMR Detection
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Solution Overview
Problem
Existing methods are limited to preparing nuclear spin singlets and/or singlet orders for individual groups and/or molecules, preventing simultaneous selective detection of multiple groups and/or molecules.
Innovation Solution
A method utilizing optimized control methods and GRAPE numerical calculation to design pulses with specific amplitudes and phases, enabling simultaneous preparation of nuclear spin singlets and/or singlet orders for multiple groups and/or molecules, followed by gradient field application to eliminate non-singlet signals and convert into observable states for detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If existing nuclear spin singlet preparation methods are used, then individual group or molecule signals can be selectively observed, but simultaneous detection of multiple groups and/or molecules is not achievable
Solution Approach 1:
The pulse sequence is divided into N small pulse units, each with different amplitude and phase values, to selectively prepare nuclear spin singlets for different molecular groups. This segmentation allows independent control of each group's singlet preparation while maintaining overall sequence efficiency
Solution Approach 2:
The pulse sequence employs periodic RF pulses with specific timing and phase modulation to simultaneously excite multiple nuclear spin systems. The periodic structure enables coherent preparation of singlet states across different frequency groups through repeated cyclic operations
2Adaptability or versatility
If multiple RF frequencies are used to excite multiple nuclear spin systems, then simultaneous preparation becomes possible, but existing techniques cannot achieve precise multi-frequency excitation
Solution Approach 1:
The pulse sequence dynamically adjusts RF amplitude and phase parameters across N pulse units to achieve precise multi-frequency excitation. Each pulse unit is calibrated with specific amplitude and phase values to target particular Larmor frequencies, enabling selective manipulation of different nuclear spin systems
Solution Approach 2:
The GRAPE numerical calculation method optimizes pulse parameters by iteratively calculating the effect of each pulse unit on the nuclear spin system. This feedback-based optimization ensures precise control of multi-frequency excitation by adjusting pulse amplitudes and phases to achieve desired singlet state preparation
3Measurement precision
If gradient field pulses are applied to eliminate non-singlet signals, then signal selectivity is improved, but detection sensitivity may be reduced
Solution Approach 1:
The pulse sequence prepares nuclear spin singlet states before applying gradient field pulses. By pre-establishing the desired quantum state, the subsequent gradient application only needs to eliminate non-singlet signals without compromising the prepared singlet, thereby maintaining both selectivity and sensitivity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables rapid, non-invasive, and sensitive simultaneous detection of multiple molecular magnetic resonance signals, enhancing signal intensity and improving interaction studies between groups and molecules, applicable in biology and medicine.
Implementation Method 1
the present invention belongs to the technical field of magnetic resonance, and specifically relates to a pulse sequence method for realizing selective detection of multiple groups and/or molecules by simultaneously preparing nuclear spin singlets and/or singlet orders
Implementation Method 2
the magnetic resonance signals of non-nuclear spin singlets and/or singlet orders in the system are eliminated by applying gradient field pulses at appropriate time
Data Source
AI summary
A pulse sequence method for realizing selective detection of multiple groups and/or molecules by simultaneously preparing nuclear spin singlets and/or singlet orders of the multiple groups and/or molecules. Taking an AGG molecule as an example, it is proposed to simultaneously prepare two pairs of uncoupled group signals of the AGG molecule into nuclear spin singlets and/or singlet orders, and eliminate magnetic resonance signals other than the nuclear spin singlets and/or singlet orders by using a pulsed gradient field, thereby realizing simultaneous selective observation of multiple group signals in the AGG molecule. Also disclosed is a method for simultaneously detecting group AGG-A in an AGG molecule and group Tau-C and group Tau-D in a Tau molecule. For the first time, the simultaneous preparation and signal selection of multiple nuclear spin singlets and/or singlet orders in a spin system is achieved. Compared with the conventional method, this method has higher sensitivity and better selectivity, and can further expand the application range of magnetic resonance.