30 results about "Gradient generator" patented technology

The invention relates to a system for fat suppression in obtaining of MR image, comprising: an RF signal generator for generating the RF pulses in an MR pulse sequence, including an RF excitation pulse and an RF re-focusing pulse after the RF excitation pulse, using one or more RF pulses for an echo signal structure. A magnetic field slice selection gradient generator generates two different slice selection magnetic field gradients to be used together with the RF excitation pulse and the RF re-focusing pulse correspondingly, wherein the first and second slice selection magnetic field gradients are substantially different in amplitude. An MR imaging control unit controls the obtaining of MR imaging data substantially suppressed in fat signal using the generated RF signals and the differentslice selection magnetic field gradients.

The invention discloses a microfluidics cell drug concentration gradient generator. The microfluidics cell drug concentration gradient generator comprises four groups of liquid inlet holes which are communicated through microchannels so as to form drug and culture medium laminar flow combinations of different volume proportions in the microchannels; one group of microchannels with micro-mixing function can ensure that drug and culture medium laminar flow combinations of different volume proportions can be fully mixed to finally form different concentrations which can form nine concentration gradients together with liquid concentrations in two channels led out from a liquid inlet directly; one group of chambers are connected with the micro-mixed channels for cell culturing and drug interaction research, and nine chambers are independent from one another. The concentration gradient generator is hardly influenced by liquid inlet rate during the generation of concentration gradients, good linear concentration gradients can be formed, and the concentration gradient generator has a simple structure and provides a brandnew platform for screening and detection of cell drugs.

A system for fat signal suppression in MR imaging comprises an RF signal generator for generating RF pulses in an MR pulse sequence using one or more RF pulses for echo signal formation including, an RF excitation pulse and an RF refocusing pulse subsequent to said RF excitation pulse. A magnetic field slice select gradient generator generates first and second different slice select magnetic field gradients for corresponding use with the RF excitation pulse and the RF refocusing pulse, respectively, the first and second different slice select magnetic field gradients having substantially different amplitudes. An MR imaging control unit directs acquisition of MR imaging data having fat signal substantially suppressed using the generated RF pulses and different slice select magnetic field gradients.

A system for use in MR imaging using tissue mechanical resonance includes an external wave generator for generating mechanical waves for transmission through patient anatomy. An RF pulse generator generates an RF pulse for exciting nuclei magnetic moments at specific spin frequencies in a particular selected anatomical region of interest. A motion encoding gradient generator generates a motion encoding gradient magnetic field within a time duration of a read-out gradient and synchronized with generation of the mechanical waves. A data processor processes data derived from radio frequency signals resulting from nuclei spin frequencies responsive to the motion encoding gradient magnetic field to detect the mechanical waves propagating through the patient anatomy.

A system acquires MR image data of a portion of patient anatomy associated with spin lattice relaxation time in a rotating frame using an RF (Radio Frequency) signal generator and a magnetic field gradient generator. The RF (Radio Frequency) signal generator generates RF excitation pulses in anatomy and enables subsequent acquisition of associated RF echo data. The magnetic field gradient generator generates anatomical volume select magnetic field gradients for phase encoding and readout RF data acquisition in a three dimensional (3D) anatomical volume. The RF signal generator and the gradient generator use in order, a saturation pulse, a T1 spin lattice relaxation rotating frame preparation pulse sequence and a spoiler gradient, in acquiring image data of the 3D volume showing luminance contrast associated with T1 spin lattice relaxation in a rotating frame.

An apparatus for generating and focusing electrons is provided. The apparatus has an emissive material configured to emit an electron, an electron target, and an electrical potential gradient generator configured to generate an electrical potential gradient within the emissive material. The electrical potential gradient is oriented so as to vary from positive to negative in the general direction toward the electron target. In operation, an electron emitted from the emissive materials is deflected away from the emissive material and generally toward the electron target. The apparatus may be incorporated in scientific analytical equipment such as an electron multiplier.

The invention discloses a 3D printing concentration gradient chip for research of a model for improving HepG2 insulin resistance by pioglitazone. An open-type micro-fluidic chip with a tree-shaped branch structure is designed, diffusion and transportation of fluid are realized by utilizing capillary action of paper-based fibers, the problem that a traditional micro-fluidic gradient generator needs external power is solved, and the gradient generator and a cell three-dimensional culture area are integrated on a same platform, so that high-throughput, repeatable and low-reagent-consumption drug screening experiment operation is realized. An experiment starts with the establishment of an insulin resistance three-dimensional cell model, discusses the reaction degree of human hepatoma carcinoma cell HepG2 insulin resistance induced by different concentrations of insulin and the level of improving HepG2 cell glucose consumption by pioglitazone, and establishes a stable insulin resistance model and a pioglitazone intervention insulin resistance model.

The invention relates to a time difference ranging radar structure with low power consumption and simple structure, and belongs to the technical field of radar structures and radar ranging. The structure comprises a digital gradient generator, a digital control type oscillator, a power amplifier, a transmitting and receiving antenna, a low-noise amplifier, an envelope detector and a time-to-digital converter. The time difference ranging radar structure can solve the problem that the radar resolution of a frequency modulated continuous wave radar is seriously limited by bandwidth, meanwhile, anoscillator in a transmitter part is controlled by an enable signal, and when a multi-bit digital signal is input, the oscillator only works in a half cycle that the multi-bit digital signal is in anupward gradient, so that the power consumption is greatly reduced; in the receiver part, the demodulation and measurement circuit part adopts an envelope detector to detect the envelope of an echo signal, and adopts a time-to-digital converter to measure the time difference, so that compared with a coherent demodulation and frequency difference measurement method of a frequency-modulated continuous wave radar, the structure is simple.

Microfluidic gradient generators that can create robust platforms that can not only be used for creating co-cultures of cells with various ratios, but also can simultaneously generate gradients of mechanical and chemical stresses. A chip utilizes microchambers embedded within channels to provide space for 3D cell culture and exposes these cells to gradients of mechanical shear stress and a chemical treatment.

The invention discloses an integrated microfluidic tissue chip and a large-scale stimulant screening analysis method. The chip is composed of a flow layer and a control layer. The flowing layer is provided with a liquid inlet, a chemical concentration gradient generator, a microcavity and an outlet. The chemical concentration gradient generator is provided with a starting end, a non-irritant unit, a flow distribution and mixing unit, an irritant unit and an outlet end, each starting end is correspondingly connected with a single liquid inlet, and each outlet end is correspondingly connected with a single microcavity; and each microcavity is correspondingly connected with a single outlet. And the control layer is provided with an air inlet, a pneumatic microstructure and an air inlet micro pipeline with a closed tail end. And all the pneumatic microstructures are communicated with the air inlet through micro pipelines with closed tail ends. Array cell localization, large-scale three-dimensional tissue-like preparation, large-scale order-of-magnitude concentration gradient type tissue-like stimulation and analysis thereof, and controllable recovery of different stimulated tissue-like samples can be realized in a single chip.

The invention discloses a nano-bubble and micron-bubble gradient generator which comprises a nozzle, a first mixing section, a first self-driven rotating impeller, a first diverging section, an air suction chamber, a second mixing section, a second self-driven rotating impeller, a second diverging section and a gas phase inlet pipe. The nozzle, the first mixing section, the first diverging section, the air suction chamber, the second mixing section and the second diverging section are sequentially connected through threads or flanges or in a welding mode. Nano bubbles are separated out at thefront half part of the device by utilizing a reinforced hydrodynamic cavitation effect, micron bubbles are formed at the rear half part of the device by adopting a jet air entraining mode, and the size and the concentration of the separated nano bubbles are adjusted by changing the rotating speed of the first self-driven rotating impeller; the second self-driven rotating impeller can change the turbulence intensity of a gas-liquid two-phase flow field so as to influence the size and dispersion degree of bubbles, and the device is simple in structure, low in energy consumption and beneficial toengineering of the device.

The invention provides a computer-aided design method of a microfluidic dilution network gradient generator, which relates to the field of microfluidic dilution network design and comprises the following steps: (1) a preliminary configuration is envisaged; (2) configuration drawing is performed; (3) the input current value and the default value of each resistor are input; (4) transient analysis isperformed; (5) circuit performance analysis is performed; (6) inspection is performed; (7) circuit optimization analysis is performed; (8) the number of variable components that need to be optimizedis reduced; (9) a circuit result diagram is output; (10) the absolute value of the mixing channel length and the flow rate is calculated; (11) the microfluidic network design drawings are obtained; (12) the design accuracy is investigated. The invention solves the problems that the current microfluidic dilution network design method relies on the experience of the designer or the performance of the computer hardware, the experimental design is time-consuming and costly, is not suitable for the large-scale design, the design accuracy is low, the optimized parameters are many, the design difficulty is great and the like.

The invention discloses a multi-channel ultra-wideband communication transceiver. The multi-channel ultra-wideband communication transceiver can be divided into four sets of sub-channels in the 6.75-10.25 GHz bandwidth, so that transmission processing of data can be carried out; therefore, a condition that multiple users or equipment work simultaneously can be satisfied; the multi-channel ultra-wideband communication transceiver is composed of a transmitter and a receiver; the transmitter is composed of a digital gradient generator, a numerically controlled oscillator and a power amplifier; and the receiver is composed of a low-noise amplifier, a double-balanced frequency adjustor and a clock and data recovery circuit. The multi-channel ultra-wideband communication transceiver disclosed by the invention can be divided into the four sets of sub-channels in the 6.75-10.25 GHz bandwidth, so that transmission processing of data is carried out; and thus, the condition that multiple users or equipment work simultaneously can be satisfied.

The invention provides a simple and convenient nuclear magnetic resonance gradient waveform distortion pre-correction method. The method comprises the following steps: 1, correcting: loading an ideal gradient waveform, namely Sgg (i = 1, t) = Sideal (t), in a gradient generator, generating distortion after the gradient waveform passes through a gradient system, obtaining a gradient waveform Svol (i = 1, t) in an imaging space through a sequence method, and estimating a gradient system response according to the Svol (i = 1, t) and the Sideal (t) to obtain a system impulse response h (t); correcting distortion of the Svol (i = 1, t) relative to the Sideal (t), performing next iteration, and updating an output gradient waveform Sgg (i + 1, t); and iterating for multiple times until the distortion of the Svol (i = 1, t) is minimum, and repeating the following steps to obtain a pre-corrected gradient waveform database. The method does not need to specially measure the frequency response of the gradient system, is more stable and reliable, does not need pre-scanning, and can adapt to scanning in any geometric orientation.