Abstract: According to an embodiment of the present disclosure, a thermionic cathode includes: a cathode body having an outer surface, and a sealing layer including one or more graphene sheets on the outer surface of the cathode body. According to another embodiment of the present disclosure, a method for manufacturing a thermionic cathode includes: depositing a sealing layer including one or more graphene sheets on an outer surface of a cathode body.

Abstract: According to an embodiment of the present disclosure, a photocathode may include: a mesh having a first surface and a second surface facing away from the first surface, and including metallic, semiconductor or ceramic mesh grid with micron-sized openings in the mesh; a photosensitive film on the first surface of the mesh and extending at least partially into the openings of the mesh; and a graphene layer including one or more graphene sheets on the second surface of the mesh.

Abstract: A tunable photocathode for use in vacuum electronic devices includes a nanostructured photoemission layer including quantum confined nanostructures, such as quantum dots. The quantum confined nanostructures can be tuned (e.g., prepared to have various characteristics or parameters) in order to independently optimize various characteristics of the electron beam emitted by the photocathode. For example, by changing the material composition, size and geometry of the quantum confined nanostructures, the energy levels of the quantum confined nanostructures in the photoemission layer can be tuned to provide a photocathode having a high quantum efficiency, low emittance, fast response time to incident light pulses, long operational lifetime, and increased environmental stability compared with conventional photocathodes and cathodes in vacuum electronic devices.

Abstract: According to an embodiment of the present disclosure, a photocathode may include: a mesh having a first surface and a second surface facing away from the first surface, and including metallic, semiconductor or ceramic mesh grid with micron-sized openings in the mesh; a photosensitive film on the first surface of the mesh and extending at least partially into the openings of the mesh; and a graphene layer including one or more graphene sheets on the second surface of the mesh.

Abstract: An electronic book system provides interfaces particularly suited to students' use of textbooks. User-controlled content is associated with portions of an electronic book. A study guide corresponding to at least some of the portions with associated user-controlled content is generated. The user can navigate between portions of the study guide and the corresponding portions of the electronic book.

Abstract: An electronic textbook system allows instructors to create custom coursebooks by integrating various materials from disparate sources. Instructors can arrange the materials, format them, provide tables of contents and indices. Payment mechanisms as well as policies for the components are integrated automatically so that the final book satisfies policy requirements for each of its component parts.

Abstract: An electronic book system provides interfaces particularly suited to students' use of textbooks. Annotations are displayed and hidden using specific gestures and through selective movement of the reader as sensed by its accelerometer. Motion of the electronic book reader below a threshold speed causes a change in display of user-selected content in a first manner and motion above the threshold speed causes a change of display in a second manner.

Abstract: A photocathode device may replenish its photoemissive coating to replace coating material that desorbs/evaporates during photoemission. A linear actuator system may regulate the release of a replenishment material vapor, such as an alkali metal, from a chamber inside the photocathode device to a porous cathode substrate. The replenishment material deposits on the inner surface of a porous membrane and effuses through the membrane to the outer surface, where it replenishes the photoemissive coating. The rate of replenishment of the photoemissive coating may be adjusted using the linear actuator system to regulate performance of the photocathode device during photoemission. Alternatively, the linear actuator system may adjust a plasma discharge gap between a cartridge containing replenishment material and a metal grid. A potential is applied between the cartridge and the grid, resulting in ejection of metal ions from the cartridge that similarly replenish the photoemissive coating.

Abstract: A photocathode device may replenish its photoemissive coating to replace coating material that desorbs/evaporates during photoemission. A linear actuator system may regulate the release of a replenishment material vapor, such as an alkali metal, from a chamber inside the photocathode device to a porous cathode substrate. The replenishment material deposits on the inner surface of a porous membrane and effuses through the membrane to the outer surface, where it replenishes the photoemissive coating. The rate of replenishment of the photoemissive coating may be adjusted using the linear actuator system to regulate performance of the photocathode device during photoemission. Alternatively, the linear actuator system may adjust a plasma discharge gap between a cartridge containing replenishment material and a metal grid. A potential is applied between the cartridge and the grid, resulting in ejection of metal ions from the cartridge that similarly replenish the photoemissive coating.

Abstract: An electronic book system provides interfaces particularly suited to students' use of textbooks. A finger press on a touch screen produces a contextual menu with user choices that relate to where the finger was pressed or what the user was recently doing with the book. A student provisionally navigates through a book by a specific gesture which, when it stops, returns the user to the previous position in the book. Annotations are displayed and hidden using specific gestures and through selective movement of the reader as sensed by its accelerometer.

Abstract: An electronic book system provides interfaces particularly suited to students' use of textbooks. A finger press on a touch screen produces a contextual menu with user choices that relate to where the finger was pressed or what the user was recently doing with the book. A student provisionally navigates through a book by a specific gesture which, when it stops, returns the user to the previous position in the book. Annotations are displayed and hidden using specific gestures and through selective movement of the reader as sensed by its accelerometer.

Abstract: Terahertz radiation source and method of producing terahertz radiation, said source comprising a junction stack, said junction stack comprising a crystalline material comprising a plurality of self-synchronized intrinsic Josephson junctions; an electrically conductive material in contact with two opposing sides of said crystalline material; and a substrate layer disposed upon at least a portion of both the crystalline material and the electrically-conductive material, wherein the crystalline material has a c-axis which is parallel to the substrate layer, and wherein the source emits at least 1 mW of power.

Abstract: An electronic book system provides interfaces particularly suited to students' use of textbooks. Annotations are displayed and hidden using specific gestures and through selective movement of the reader as sensed by its accelerometer. Motion of the electronic book reader below a threshold speed causes a change in display of user-selected content in a first manner and motion above the threshold speed causes a change of display in a second manner.

Abstract: An electronic book system provides interfaces particularly suited to students' use of textbooks. User-controlled content is associated with portions of an electronic book. A study guide corresponding to at least some of the portions with associated user-controlled content is generated. The user can navigate between portions of the study guide and the corresponding portions of the electronic book.

Abstract: An electronic book system provides interfaces particularly suited to students' use of textbooks. A finger press on a touch screen produces a contextual menu with user choices that relate to where the finger was pressed or what the user was recently doing with the book. A student provisionally navigates through a book by a specific gesture which, when it stops, returns the user to the previous position in the book. Annotations are displayed and hidden using specific gestures and through selective movement of the reader as sensed by its accelerometer.

Abstract: An electronic book system provides interfaces particularly suited to students' use of textbooks. A finger press on a touch screen produces a contextual menu with user choices that relate to where the finger was pressed or what the user was recently doing with the book. A student provisionally navigates through a book by a specific gesture which, when it stops, returns the user to the previous position in the book. Annotations are displayed and hidden using specific gestures and through selective movement of the reader as sensed by its accelerometer.

Abstract: An electronic book system provides interfaces particularly suited to students' use of textbooks. A finger press on a touch screen produces a contextual menu with user choices that relate to where the finger was pressed or what the user was recently doing with the book. A student provisionally navigates through a book by a specific gesture which, when it stops, returns the user to the previous position in the book. Annotations are displayed and hidden using specific gestures and through selective movement of the reader as sensed by its accelerometer.