Abstract: The present disclosure relates to methods of fabricating a porous structure, such as a porous silicon carbide structure. The methods can include a step of providing a structure to be rendered porous, and a step of providing an etching solution. The methods can also include a step of electrochemically etching the structure to produce pores through at least a region of the structure, resulting in the formation of a porous structure. The morphology of the porous structure can be controlled by one or more parameters of the electrochemical etching process, such as the strength of the etching solution and/or the applied voltage.

Abstract: A method, apparatus, and system include a cooling system comprising a payload refrigeration unit, control refrigeration unit, and a signal interface. The payload refrigeration unit has a set of payload cooling components that operate to cool a payload. The control refrigeration unit has a set of control circuit cooling components in a control circuit. The signal interface connecting the payload is located in the payload refrigeration unit in the control circuit located in the control refrigeration unit.

Abstract: The present disclosure relates to methods of fabricating a porous structure, such as a porous silicon carbide structure. The methods can include a step of providing a structure to be rendered porous, and a step of providing an etching solution. The methods can also include a step of electrochemically etching the structure to produce pores through at least a region of the structure, resulting in the formation of a porous structure. The morphology of the porous structure can be controlled by one or more parameters of the electrochemical etching process, such as the strength of the etching solution and/or the applied voltage.

Abstract: The present disclosure relates to methods of fabricating a porous structure, such as a porous silicon carbide structure. The methods can include a step of providing a structure to be rendered porous, and a step of providing an etching solution. The methods can also include a step of electrochemically etching the structure to produce pores through at least a region of the structure, resulting in the formation of a porous structure. The morphology of the porous structure can be controlled by one or more parameters of the electrochemical etching process, such as the strength of the etching solution and/or the applied voltage.

Abstract: The present disclosure relates to methods of fabricating a porous structure, such as a porous silicon carbide structure. The methods can include a step of providing a structure to be rendered porous, and a step of providing an etching solution. The methods can also include a step of electrochemically etching the structure to produce pores through at least a region of the structure, resulting in the formation of a porous structure. The morphology of the porous structure can be controlled by one or more parameters of the electrochemical etching process, such as the strength of the etching solution and/or the applied voltage.

Abstract: A detection pixel includes a material that is chosen so that its (averaged) atomic number density leads to the Compton process being the dominant scattering mechanism in response to incident photons, leading to production of Compton electrons with sufficient number and kinetic energy to produce an electric or magnetic response in the material. The incident photon and Compton electrons each have a characteristic travel distance in the material, and the detection pixel has at least one dimension that is selected according to a range defined by these characteristic travel distances. The detection pixels may be arranged in an array for imaging.

Abstract: The present disclosure relates to methods of making a transition metal dichalcogenide. The methods can include a step of depositing a transition metal onto a substrate to form an epitaxial transition metal layer. The methods can also include a step of depositing a chalcogen onto the epitaxial transition metal layer, and a step of reacting the chalcogen with the epitaxial transition metal layer to form a transition metal dichalcogenide. In some instances, the chalcogen is reacted with the epitaxial transition metal layer at a temperature of between about 300° C. and 600° C., between about 300° C. and 550° C., between about 300° C. and 500° C., between about 300° C. and 450° C., or between about 300° C. and 400° C.

Abstract: A detection pixel includes a material that is chosen so that its (averaged) atomic number density leads to the Compton process being the dominant scattering mechanism in response to incident photons, leading to production of Compton electrons with sufficient number and kinetic energy to produce an electric or magnetic response in the material. The incident photon and Compton electrons each have a characteristic travel distance in the material, and the detection pixel has at least one dimension that is selected according to a range defined by these characteristic travel distances. The detection pixels may be arranged in an array for imaging.

Abstract: A cold cathode field emission electron source capable of emission at levels comparable to thermal sources is described. Emission in excess of 6 A/cm2 at 7.5 V/?m is demonstrated in a macroscopic emitter array. The emitter has a monolithic and rigid porous semiconductor nanostructure with uniformly distributed emission sites, and is fabricated through a room temperature process which allows for control of emission properties. These electron sources can be used in a wide range of applications, including microwave electronics and x-ray imaging for medicine and security.

Abstract: The present disclosure relates to methods of making a transition metal dichalcogenide. The methods can include a step of depositing a transition metal onto a substrate to form an epitaxial transition metal layer. The methods can also include a step of depositing a chalcogen onto the epitaxial transition metal layer, and a step of reacting the chalcogen with the epitaxial transition metal layer to form a transition metal dichalcogenide. In some instances, the chalcogen is reacted with the epitaxial transition metal layer at a temperature of between about 300° C. and 600° C., between about 300° C. and 550° C., between about 300° C. and 500° C., between about 300° C. and 450° C., or between about 300° C. and 400° C.

Abstract: A cold cathode field emission electron source capable of emission at levels comparable to thermal sources is described. Emission in excess of 6 A/cm2 at 7.5 V/?m is demonstrated in a macroscopic emitter array. The emitter has a monolithic and rigid porous semiconductor nanostructure with uniformly distributed emission sites, and is fabricated through a room temperature process which allows for control of emission properties. These electron sources can be used in a wide range of applications, including microwave electronics and x-ray imaging for medicine and security.

Abstract: A cold cathode field emission electron source capable of emission at levels comparable to thermal sources is described. Emission in excess of 6 A/cm2 at 7.5 V/?m is demonstrated in a macroscopic emitter array. The emitter has a monolithic and rigid porous semiconductor nanostructure with uniformly distributed emission sites, and is fabricated through a room temperature process which allows for control of emission properties. These electron sources can be used in a wide range of applications, including microwave electronics and x-ray imaging for medicine and security.

Abstract: A cold cathode field emission electron source capable of emission at levels comparable to thermal sources is described. Emission in excess of 6 A/cm2 at 7.5 V/?m is demonstrated in a macroscopic emitter array. The emitter is comprised of a monolithic and rigid porous semiconductor nanostructure with uniformly distributed emission sites, and is fabricated through a room temperature process which allows for control of emission properties. These electron sources can be used in a wide range of applications, including microwave electronics and x-ray imaging for medicine and security.

Abstract: A cold cathode field emission electron source capable of emission at levels comparable to thermal sources is described. Emission in excess of 6 A/cm2 at 7.5 V/?m is demonstrated in a macroscopic emitter array. The emitter is comprised of a monolithic and rigid porous semiconductor nanostructure with uniformly distributed emission sites, and is fabricated through a room temperature process which allows for control of emission properties. These electron sources can be used in a wide range of applications, including microwave electronics and x-ray imaging for medicine and security.

Abstract: A variable temperature assembly for scanning probe microscopy (SPM) is described which minimizes or eliminates motion of the sample caused by the thermal expansion or contraction of the sample holder assembly and platform/scanning stage on which the assembly is mounted, and minimizes heating or cooling of the platform/stage. In heater form, the variable temperature assembly includes a thin boron nitride puck with one or more high-resistivity wires embedded along an underside of the puck. The puck is suspended from its polished top surface by posts that are secured to the microscope stage. All thermal expansion of the puck occurs in the downward direction, away from the SPM probe-sample interface, thus eliminating relative motion between the probe tip and sample surface. The top surface of the puck remains stationary as a result of the unique geometry of the posts and the puck-post attachment configuration described herein.

Abstract: The disclosure relates to a material having a textured surface and exhibiting absorption of electromagnetic waves with gigahertz frequencies. The textured surface can comprise a plurality of protrusions that can permit absorption of such waves. Morphology of the plurality of protrusions can control the absorption properties, e.g., absorption coefficients or specific frequency of absorbed electromagnetic radiation, of such materials. The material can comprise an electrically conductive thermoplastic composite. At least some of the protrusions can be formed of such composite. The material having the texture surface can exhibit broadband absorption.

Abstract: A cold cathode field emission electron source capable of emission at levels comparable to thermal sources is described. Emission in excess of 6 A/cm2 at 7.5 V/?m is demonstrated in a macroscopic emitter array. The emitter is comprised of a monolithic and rigid porous semiconductor nanostructure with uniformly distributed emission sites, and is fabricated through a room temperature process which allows for control of emission properties. These electron sources can be used in a wide range of applications, including microwave electronics and x-ray imaging for medicine and security.

Abstract: A device includes a first thermally conductive substrate having a first patterned electrode disposed thereon and a second thermally conductive substrate having a second patterned electrode disposed thereon, wherein the first and second thermally conductive substrates are arranged such that the first and second patterned electrodes are adjacent to one another. The device includes a plurality of nanowires disposed between the first and second patterned electrodes, wherein the plurality of nanowires is formed of a thermoelectric material. The device also includes a joining material disposed between the plurality of nanowires and at least one of the first and second patterned electrodes.

Abstract: A composition including a polycrystalline metal nitride having a number of grains is provided. These grains have a columnar structure with one or more properties such as, an average grain size, a tilt angle, an impurity content, a porosity, a density, and an atomic fraction of the metal in the metal nitride.

Abstract: A composition including a polycrystalline metal nitride having a number of grains is provided. These grains have a columnar structure with one or more properties such as, an average grain size, a tilt angle, an impurity content, a porosity, a density, and an atomic fraction of the metal in the metal nitride. An apparatus for preparing a metal nitride is provided. The apparatus may include a housing having an interior surface that defines a chamber and an energy source to supply energy to the chamber. A first inlet may be provided to flow a nitrogen-containing gas into the chamber. Raw materials may be introduced into the chamber through a raw material inlet. A second inlet may be provided to flow in a halide-containing gas in the chamber. The apparatus may further include a controller, which communicates with the various components of the apparatus such as, sensors, valves, and energy source, and may optimize and control the reaction.