Abstract: A resonator, a filter and a duplexer, which relate to the technical field of resonators. The resonator includes: a substrate, and a lower electrode layer, a piezoelectric layer and an upper electrode layer, which are sequentially formed on the substrate, wherein an acoustic reflection structure is formed on a surface of the substrate that is close to the lower electrode layer, and an overlapping region of the acoustic reflection structure, the lower electrode layer, the piezoelectric layer and the upper electrode layer along a stacking direction forms a resonant region; and in the resonant region, the surface, which is away from the substrate, of at least one of the lower electrode layer, the piezoelectric layer and the upper electrode layer is etched to form an etched region, the depth of the etched region is less than the thickness of an etched layer, and the area of the etched region is less than the area of the resonant region.

Abstract: Provided are a bulk acoustic resonator and a filter. The bulk acoustic resonator includes a substrate having a cavity, and a bottom electrode, a piezoelectric layer and a top electrode that are sequentially arranged on the substrate, where an overlapping area of orthographic projections of the bottom electrode, the piezoelectric layer and the top electrode on the substrate forms a resonance area; and in the resonance area, an outline shape of the orthographic projection of each of the bottom electrode and the top electrode on the substrate is a closed figure formed by connecting M arcs end to end, and the closed figure is an axisymmetric figure, where M is an integer greater than or equal to 2, and the arcs include a concave arc that is concave toward a center of the resonance area and a convex arc that is convex away from the center of the resonance area.

Abstract: The present application provides a preparation method of racemic nicotine, including the following steps: Nicotinyl chloride and methylamine are reacted under alkaline conditions to obtain methylnicotinamide, then condensed with monochloroacetone to obtain N-methyl-N-(2-oxopropyl) nicotinamide, then self-aldol condensed to obtain 1-methyl-5-(pyridin-3-yl)-1,2-dihydro-3H-pyrrol-3-one, and finally reduced to obtain racemic nicotine.

Abstract: This application provide quantum key distribution methods, devices, and storage media. In an implementation, a method comprises: determining, based on a first mapping, a first quantum key of N first quantum keys corresponding to an ith node on a target routing path; determining, based on a second mapping, a second quantum key of N second quantum keys corresponding to the ith node; and generating, by the ith node based on the first quantum key corresponding to the ith node and the second quantum key corresponding to the ith node, a third quantum key corresponding to the ith node on the target routing path.

Abstract: Systems and methods for improved heating, ventilation, air conditioning, and refrigeration systems incorporating a plurality of refrigerant circuits. The system can include a compressor having a first compression chamber, a second compression chamber, and a motor. The system can further include a heat exchanger having a first set of microchannel coils and a second set of microchannel coils. The system can have a first circuit fluidly coupled between the first compression chamber and the first set of microchannel coils and a second circuit fluidly coupled between the second compression chamber and the second set of microchannel coils. Further, the first circuit comprises a first refrigerant and the second circuit comprises a second refrigerant.

Abstract: Embodiments include heat pump systems with gas bypasses and related methods. In one embodiment, a system may include a gas bypass tank having a bypass inlet, a liquid outlet, and a vapor outlet, and a first splitting valve having a first splitter outlet in fluid communication with the bypass inlet, a first splitter inlet in fluid communication with the liquid outlet, and a first switching path configured to switch between a first conduit path in fluid communication with a first coil system and a second conduit path in fluid communication with a second coil system.

Abstract: The present application discloses a synthesis method of chiral nicotine from nicotinate and ?-butyrolactone, including the following steps: Step S1: performing condensation under an alkaline condition, and performing ring opening reaction with hydrochloric acid; Step S2: reacting with (+)-B-diisopinocampheyl chloroborane to produce a chiral hydroxyl group; Step S3: performing a chlorination reaction; and Step S4: performing cyclization under an alkaline condition to obtain the chiral nicotine. In the present application, nicotinate and ?-butyrolactone, both cheap and readily available, are used as raw materials, so as to reduce the production cost of (S)-nicotine. (+)-B-diisopinocampheyl chloroborane is used to reduce a carbonyl group of an intermediate to obtain a target chiral center.

Abstract: The present disclosure provides a refrigeration device including a circuit having an evaporator, a compressor, a condenser, and an expansion valve orderly connected by a refrigerant flow path. The refrigeration device further includes a first sensor to sense ambient temperature, second sensor to sense evaporator inlet temperature, a microwave module disposed proximal to the evaporator to generate microwaves, and a controller coupled to the first sensor, the second sensor and the microwave module. The controller determines whether a difference in temperature value between the ambient temperature and the evaporator inlet temperature is equal to or greater than a first predetermined temperature value, and initiates operation of the microwave module to heat an inlet of the evaporator when the difference in temperature value between the ambient temperature and the evaporator inlet temperature is equal to or greater than the first predetermined temperature value.

Abstract: A method for preparing chiral synthetic nicotine includes the following steps: Step S1. condensing nicotinic acid ester and ?-butyrolactone under the action of alkaline condensate in organic solvent I to obtain the first mixture; Step S2. performing a ring-opening reaction to the first mixture obtained in Step S1 by adding an acidic substance to obtain a second mixture; Step S3. separating 4-chloro-1-(3-pyridine)-1-butanone from the second mixture obtained in Step S2, reacting with chiral tert-butyl sulfinamide to obtain chiral N-(4-chloro-1-(pyridin-3-yl)butene) -2-methylpropane-2-sulfinamide; Step S4: reacting the chiral N-(4-chloro-1-(pyridin-3-yl) butene)-2-methylpropane-2-sulfenamide with a reducing agent, and then cyclizing under the action of hydrogen halide to obtain a chiral demethylized nicotine; and Step S5: performing methylamination to the chiral demethylized nicotine to obtain a chiral nicotine.

Abstract: The present invention provides a preparation method for synthesizing S-nicotine from glutarate, including: reacting nicotinate with glutarate in the presence of a base catalyst to obtain 5-carbonyl-5-(pyridin-3-yl)pentanoic acid, reacting with an amination reagent to obtain 5-oxo-5-(pyridin-3-yl)pentanamide, performing Hofmann degradation on to obtain 4-amino-1-(pyridin-3-yl)butanone, reducing a carbonyl group of the 4-amino-1-(pyridin-3-yl)butanone by using (+)-B-diisopinocampheyl chloroborane to obtain (S)-4-amino-1-(pyridin-3-yl)butan-1-ol, performing chlorination and cyclization to obtain S-demethylnicotine, and finally performing amine methylation to obtain S-nicotine.

Abstract: Systems and methods for pressure expanding a tube to fit a heat exchanger fin are disclosed. The systems can include one or more pressure relief devices, and each pressure relief device can be configured to release at least some pressurized fluid via a respective auxiliary flow path in response to a pressure of the pressurized fluid being greater than a predetermined pressure relief threshold.

Abstract: Heat pump systems with a gas bypass tank and that operate in both heating and cooling modes are disclosed. The systems include a first splitting valve that can route liquid refrigerant to either the indoor coil or the outdoor coil, depending on whether the heat pump system is in heating or cooling mode. An expansion valve in the system can lower the pressure of liquid refrigerant leaving a condenser, thereby creating a two-phase fluid comprising liquid refrigerant and vaporized refrigerant. The gas bypass tank can separate liquid refrigerant from vaporized refrigerant. The liquid refrigerant can be supplied to the evaporator of the system, while the vaporized refrigerant can be bypassed to a compressor. The first splitting valve can include a first plurality of switching paths that route the separated liquid refrigerant to either the outdoor coil or the indoor coil.

Abstract: A compound represented by formula II or a pharmaceutically acceptable salt thereof, and a preparation method therefor. The compound represented by formula II is an antagonist of a neurokinin-1 receptor, can be used for treating diseases related to the neurokinin-1 receptor, and can avoid hemolytic effects of drugs and reduce the side effects of drug administration.

Abstract: Provided are a live detection method and apparatus for a high-voltage switch cabinet. The live detection apparatus for a high-voltage switch cabinet includes a robot body and a back-end server. The robot body includes a host module, a power module, a detection module and a motion module. The power module is electrically connected to the host module and the motion module. The host module is communicably connected to the motion module and the detection module. The detection module includes a visible light camera, an infrared thermal imager, an non-contacting ultrasonic sensor and an ultrahigh-frequency sensor. The motion module includes a horizontal motion module, a vertical motion module and a rotating motion module. The horizontal motion module includes a motor-driven carrier and a laser navigation system. The vertical motion module is secured to the motor-driven carrier.

Abstract: The disclosed technology includes devices, systems, and methods for a battery-integrated heat pump system. The disclosed technology can include a heat pump system having an indoor heat exchanger coil, an outdoor heat exchanger coil, and a compressor. The disclosed technology can further include a third heat exchanger coil, a battery, and a pump configured to circulate a fluid through the third heat exchanger coil and the battery. The disclosed technology can be configured to manage the temperature of the battery by operating the pump to facilitate heat transfer between the refrigerant and the fluid to heat or cool the battery.

Abstract: The disclosed technology includes devices, systems, and methods for a battery-integrated heat pump system. The disclosed technology can include a heat pump system having a battery, a compressor, and a variable speed drive in electrical communication with the battery and the compressor. The variable speed drive can be configured to control a speed of the compressor. The heat pump system can include a fan that can be configured to move air across a heat exchanger coil of the heat pump system and the battery can be located in an airflow path of the fan such that the fan can also move air across the battery to regulate a temperature of the battery.

Abstract: A key generation method includes modulating a first key to a first light source signal, to obtain a modulated optical signal, splitting the modulated optical signal, to obtain a first sub modulated optical signal and a second sub modulated optical signal, attenuating the first sub modulated optical signal such that a quantity of photons included in each period of the first sub modulated optical signal is less than a preset value, and sending an attenuated first sub modulated optical signal to a receive-end device, and obtaining a second key carried in the second sub modulated optical signal, and storing the second key.

Abstract: A heat exchanger fin is disclosed. The fin can include a fin portion and a collar portion defining a fin aperture that has a central axis passing therethrough. The collar portion can include a nesting end including a nesting portion and a receiving end that (i) is located apart from the nesting end in an axial direction and (ii) comprises one or more bends to form an overhang portion that defines a gap located radially inward of the overhang portion. The gap can be dimensioned to at least partially receive the nesting portion. The collar portion can also include a contact portion extending between the nesting end and the receiving end, and the contact portion can be configured to abut an outer surface of a tube when the tube is at least partially inserted into the fin aperture.

Abstract: The disclosure discloses a two-dimensional high-performance resonator, which is specifically an ultra-high-frequency resonator structure capable of improving an electromechanical coupling coefficient of the resonator. The resonator includes a piezoelectric layer, where an electrode layer is distributed on the upper surface of the piezoelectric layer, the electrode layer includes a plurality of electrodes arranged in a horizontal direction with a distance therebetween greater than four wavelengths, and a bridge structure is arranged on an upper portion of the electrode layer. The resonator structure can effectively improve the resonance frequency and the electromechanical coupling coefficient of the resonator, and can meet the requirements of the 5G market, and the quality factor is greatly improved.

Abstract: Systems and methods for pressure expanding a tube to fit a heat exchanger fin are disclosed. The systems can include one or more pressure relief devices, and each pressure relief device can be configured to release at least some pressurized fluid via a respective auxiliary flow path in response to a pressure of the pressurized fluid being greater than a predetermined pressure relief threshold.