A method and system of using a type of wave rotor to reform a hydrocarbon fluid using pressure waves within the wave rotor to reformulate a hydrocarbon fluid, such as methane or the like, into a lighter hydrocarbon, hydrogen, or, in some instances, hydrogen, partially decomposed hydrocarbon fluid and carbon solids.

A method and system of using a type of wave rotor to reform a hydrocarbon fluid using pressure waves within the wave rotor to reformulate a hydrocarbon fluid, such as methane or the like, into a lighter hydrocarbon, hydrogen, or, in some instances, hydrogen, partially decomposed hydrocarbon fluid and carbon solids.

One variation of a method includes: ingesting an air sample captured during an air capture period at a target location for collection of a first mixture including carbon dioxide and a first concentration of impurities; conveying the first mixture through a liquefaction unit to generate a second mixture including carbon dioxide and a second concentration of impurities less than the first concentration of impurities; in a methanation reactor, mixing the second mixture with hydrogen to generate a first hydrocarbon mixture comprising a third concentration of impurities comprising nitrogen, carbon dioxide, and hydrogen; conveying the first hydrocarbon mixture through a separation unit configured to remove impurities from the first hydrocarbon mixture to generate a second hydrocarbon a fourth concentration of impurities less than the third concentration of impurities; and depositing the second hydrocarbon mixture in a diamond reactor containing a set of diamond seeds to generate a first set of diamonds.

One variation of a method includes: ingesting an air sample captured during an air capture period at a target location for collection of a first mixture including carbon dioxide and a first concentration of impurities; conveying the first mixture through a liquefaction unit to generate a second mixture including carbon dioxide and a second concentration of impurities less than the first concentration of impurities; in a methanation reactor, mixing the second mixture with hydrogen to generate a first hydrocarbon mixture comprising a third concentration of impurities comprising nitrogen, carbon dioxide, and hydrogen; conveying the first hydrocarbon mixture through a separation unit configured to remove impurities from the first hydrocarbon mixture to generate a second hydrocarbon a fourth concentration of impurities less than the third concentration of impurities; and depositing the second hydrocarbon mixture in a diamond reactor containing a set of diamond seeds to generate a first set of diamonds.

One variation of a diamond composition includes carbon: including a first amount of carbon-13 isotopes and a second amount of carbon-12 isotopes; and sourced from a hydrocarbon mixture including hydrocarbons and formed via methanation of a carbon dioxide mixture. The carbon dioxide mixture: sourced from a sample of air including carbon dioxide and impurities; conveyed through a separation unit configured to remove impurities; including carbon dioxide and impurities; conveyed through a distillation column configured to regulate amounts of carbon-13 isotopes and carbon-12 isotopes; and exhibiting a target ratio of carbon-13 isotopes to carbon-12 isotopes at an outlet of the distillation column. The diamond composition: formed via chemical vapor deposition; and exhibiting an isotopic signature defining a final ratio of the first amount of carbon-13 isotopes to the second amount of carbon-12 isotopes within a first target range corresponding to the target ratio exhibited by the carbon dioxide mixture.

A polycrystalline element includes a table formed of polycrystalline diamond. The table includes a first surface; a second surface spaced apart from the first surface; and at least one side extending between the first surface and the second surface. The table also includes a plurality of extensions also formed of polycrystalline diamond, wherein at least one extension of the plurality of extensions extends away from at least one of the first surface and the at least one side. Optionally, the polycrystalline diamond of at least one extension of the plurality of extensions is contiguous with the polycrystalline diamond of the table. The polycrystalline element may be used in downhole tools for boring and well drilling, machine tools, and bearings.

A polycrystalline element includes a table formed of polycrystalline diamond. The table includes a first surface; a second surface spaced apart from the first surface; and at least one side extending between the first surface and the second surface. The table also includes a plurality of extensions also formed of polycrystalline diamond, wherein at least one extension of the plurality of extensions extends away from at least one of the first surface and the at least one side. Optionally, the polycrystalline diamond of at least one extension of the plurality of extensions is contiguous with the polycrystalline diamond of the table. The polycrystalline element may be used in downhole tools for boring and well drilling, machine tools, and bearings.

A method for manufacturing diamond substrate of using source gas containing hydrocarbon gas and hydrogen gas to form diamond crystal on an underlying substrate by CVD method, to form a diamond crystal layer having nitrogen-vacancy centers in at least part of the diamond crystal, nitrogen or nitride gas is mixed in the source gas, wherein the source gas is: 0.005 volume % or more and 6.000 volume % or less of the hydrocarbon gas; 93.500 volume % or more and less than 99.995 volume % of the hydrogen gas; and 5.0×10.sup.−5 volume % or more and 5.0×10.sup.−1 volume % or less of the nitrogen gas or the nitride gas, and the diamond crystal layer having the nitrogen-vacancy centers is formed. A method for manufacturing a diamond substrate to form an underlying substrate, a diamond crystal having a dense nitrogen-vacancy centers (NVCs) with an orientation of NV axis by performing the CVD.

According to one embodiment, an electron-emitting element includes a first member and a second member. The first member includes a semiconductor member of an n-type. The second member includes a diamond member a p-type and includes at least one selected from the group consisting of diamond and graphite. The semiconductor member includes at least one selected from the group consisting of a first material, a second material, and a third material. The first material includes nitrogen and at least one selected from the group consisting of B, Al, In, and Ga. The second material includes at least one selected from the group consisting of ZnO and ZnMgO. The third material includes at least one selected from the group consisting of BaTiO.sub.3, PbTiO.sub.3, Pb(Zr.sub.x, Ti.sub.1-x)O.sub.3, KNbO.sub.3, LiNbO.sub.3, LiTaO.sub.3, Na.sub.xWO.sub.3, Zn.sub.2O.sub.3, Ba.sub.2NaNb.sub.5O.sub.5, Pb.sub.2KNb.sub.5O.sub.15, and Li.sub.2B.sub.4O.sub.7.

According to one embodiment, an electron-emitting element includes a first member and a second member. The first member includes a semiconductor member of an n-type. The second member includes a diamond member a p-type and includes at least one selected from the group consisting of diamond and graphite. The semiconductor member includes at least one selected from the group consisting of a first material, a second material, and a third material. The first material includes nitrogen and at least one selected from the group consisting of B, Al, In, and Ga. The second material includes at least one selected from the group consisting of ZnO and ZnMgO. The third material includes at least one selected from the group consisting of BaTiO.sub.3, PbTiO.sub.3, Pb(Zr.sub.x, Ti.sub.1-x)O.sub.3, KNbO.sub.3, LiNbO.sub.3, LiTaO.sub.3, Na.sub.xWO.sub.3, Zn.sub.2O.sub.3, Ba.sub.2NaNb.sub.5O.sub.5, Pb.sub.2KNb.sub.5O.sub.15, and Li.sub.2B.sub.4O.sub.7.