Abstract: The present disclosure belongs to the technical field of biochemical engineering, and relates to a preparation method of ?-galactosidase. The preparation method includes the following steps: step 1, seeding Bacillus circulans into a Luria-Bertani (LB) medium for culture and activation and then into a seed tank for culture to obtain a seed culture broth; step 2, introducing the seed culture broth into a fermentor containing a fermentation medium for fermentation to obtain a fermentation broth of B. circulans; and step 3, filtering or centrifuging the fermentation broth of B. circulans to remove cells to obtain a ?-galactosidase liquid; the fermentation medium includes lactose, galactose, phytone, corn meal, yeast extract, a phosphate salt, a carbonate salt, and water. According to the method, fermentation time is short, production period is shortened, and specific activity of the resulting enzyme liquid is high.

Abstract: A method and system for analyzing a seismically active field based on expansion of an empirical orthogonal function is provided. The research region of the seismic active field is gridded at equal intervals for the preset research region of a seismic active field; a seismic active field function matrix correlated with the research region of the seismic active field spatially and temporally is constructed according to the gridding of the research region of the seismic active field; and the seismic active field function matrix is expanded with an empirical orthogonal function to obtain a main typical field and a temporal factor thereof, and an anomaly on the temporal factor of the seismic active field is analyzed with a method index, a parameter index and an anomaly index.

Abstract: The invention discloses a brake cable take-up device of folding mobility aids, comprising a frame, a brake cable, and a cable take-up device, wherein the cable take-up device comprises a first pin shaft, a coil spring, and a second pin shaft; the first pin shaft and the second pin shaft are arranged on the frame with a gap; the coil spring comprises an inner end and an outer end; the inner end is rotatably sleeved on the first pin shaft; the outer end is provided with a pulling ring; the brake cable extends from one end of the frame to the cable take-up device, and is movably wound around the second pin shaft and the pulling ring and then extends to the other end of the frame; the frame comprises a longitudinal pipe, and the lower end of the longitudinal pipe is connected with a horizontal pipe.

Abstract: Disclosed is a disposable stepless speed regulation medical pulse irrigator with an LED lamp, including an upper handle, a lower handle, a pump body, a fluid tube, stepless speed regulation control parts, a spray nozzle part, a power supply part and an LED lamp. The pump body is arranged inside the upper handle; the left side of the pump body is connected with a piston; and the bottom end of the piston is provided with a big gear. In a pulse irrigating process of a wound, the disposable stepless speed regulation medical pulse irrigator with the LED lamp can use a continuous regulatable flushing speed and pressure to reduce the discomfort of a patient with this instrument according to the wound pain sensitivity of the patient, and can improve the wound cleansing efficiency and relieve the working load of medical staff at the same time.

Abstract: A method and system for analyzing a seismically active field based on expansion of an empirical orthogonal function is provided. The research region of the seismic active field is gridded at equal intervals for the preset research region of a seismic active field; a seismic active field function matrix correlated with the research region of the seismic active field spatially and temporally is constructed according to the gridding of the research region of the seismic active field; and the seismic active field function matrix is expanded with an empirical orthogonal function to obtain a main typical field and a temporal factor thereof, and an anomaly on the temporal factor of the seismic active field is analyzed with a method index, a parameter index and an anomaly index.

Abstract: A method for generating an actuation signal for a light source is provided. A random phase delay for each period of an input signal is generated, where each period is a predetermined length. Each phase delay is added to a predetermined actuation period to generate a sum. The sum is compared to the predetermined length. At least one turn-on and at least one turn-off for each period of the input signal is calculated from the comparison of the sum to the predetermined length, and the actuation signal having each turn-on and each turn-off is generated.

Abstract: One embodiment of the invention includes a system for regulating an output voltage of a power converter. The system comprises an error amplifier that compares a feedback voltage associated with the output voltage with a reference voltage to generate an error signal that is employed to control a magnitude of the output voltage. The system also comprises a plurality of sample and hold circuits each configured to sample an error amplifier output voltage to provide the error signal. The system further comprises a switching controller configured to control switching of the error amplifier output voltage between each of the plurality of sample and hold circuits in response to a change in an output load of the power converter.

Abstract: One embodiment of the invention includes a power regulator system. The system comprises at least one current regulator configured to maintain a substantially constant current flow through each of at least one series connected light emitting diode (LED) string. The system also comprises a power converter configured to generate an output voltage to provide power to the at least one current regulator and the at least one series connected LED string. The system further comprises a voltage regulator configured to determine a voltage that provides power to the at least one current regulator and to adjust the output voltage based on the determined voltage to mitigate power loss due to excessive voltage provided to power the at least one current regulator.

Abstract: A method for generating an actuation signal for a light source is provided. A random phase delay for each period of an input signal is generated, where each period is a predetermined length. Each phase delay is added to a predetermined actuation period to generate a sum. The sum is compared to the predetermined length. At least one turn-on and at least one turn-off for each period of the input signal is calculated from the comparison of the sum to the predetermined length, and the actuation signal having each turn-on and each turn-off is generated.

Abstract: One embodiment of the invention includes a system for regulating an output voltage of a power converter. The system comprises an error amplifier that compares a feedback voltage associated with the output voltage with a reference voltage to generate an error signal that is employed to control a magnitude of the output voltage. The system also comprises a plurality of sample and hold circuits each configured to sample an error amplifier output voltage to provide the error signal. The system further comprises a switching controller configured to control switching of the error amplifier output voltage between each of the plurality of sample and hold circuits in response to a change in an output load of the power converter.

Abstract: One embodiment of the invention includes a power regulator system. The system comprises at least one current regulator configured to maintain a substantially constant current flow through each of at least one series connected light emitting diode (LED) string. The system also comprises a power converter configured to generate an output voltage to provide power to the at least one current regulator and the at least one series connected LED string. The system further comprises a voltage regulator configured to determine a voltage that provides power to the at least one current regulator and to adjust the output voltage based on the determined voltage to mitigate power loss due to excessive voltage provided to power the at least one current regulator.