DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
Claim Amendments
Applicant’s cancellation of claims 16-17 and amendments to claim 1, 9 and 23 in the reply filed 29 January 2026 are acknowledged. These amendments overcome the prior claim objections, which are withdrawn.
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention.
Claims 1, 4-10, 15 and 21-23 are rejected under 35 U.S.C. 103 as being obvious over Tranter et al. (US 2006/0057038 A1) in view of Robertson et al. (WO 2019/183724 A1), Vasiliev et al. (Radiochim. Acta 2019, 107(12), 1203–1211), Abrão et al. (J. Alloys Compounds 2001, 323–324, 53–56), Abdellah et al. (Radiochemistry 2020, 62(3), 347–358) and Vaziri Hassas et al. (US 2023/0340639 A1; effective filing date of 30 January 2020).
Regarding claim 1, Tranter teaches a method for generating 225Ac from 229Th (a method of producing an actinium-225/bismuth-213 product from a material containing thorium-229; abstract) comprising creating a first suspension by adding a solid 229Th precipitate to an acidic cover liquid solution to create a first suspension (storage solution for storage of collected precipitates comprising parent isotope thorium-229 can comprise nitric acid; [0034]). While the claim limitations seem to imply that the suspension is created prior to being introduced to a vessel, one of ordinary skill in the art would recognize that a suspension must be created in some vessel. With respect to the order of steps, it is noted that the courts have held that any order of performing process steps is prima facie obvious in the absence of new or unexpected results (In re Gibson, 39 F.2d 975, 5 USPQ 230 (CCPA 1930); Ex parte Rubin, 128 USPQ 440 (Bd. App. 1959)). See MPEP §2144.04 IV C. Thus, the claimed order of creating the first suspension then providing the first suspension comprising solid 229Th precipitate and the cover liquid solution to a vessel is an obvious variant of the steps of the cited prior art where the suspension (storage solution) is created, necessarily, in a vessel.
Tranter also teaches storing the first suspension for a first period of time during which the at least some of 229Th decays into 225Ac (storing a precipitate …for a period of sufficient time length to generate a decay product…actinium-225 can be generated and collected from a Th-229 comprising precipitate; [0031]);
separating the solid 229Th precipitate from at least some of the cover liquid solution of the first suspension to obtain a first quantity of separated solid 229Th precipitate and a first liquid solution containing at least some 225Ac (collection of a decay product can comprise separation of a liquid fraction from a solid fraction by, for example, utilization of one or more filtration techniques; [0037]);
after separating the first quantity of separated solid 229Th precipitate from the cover liquid, adding an amount of fresh cover liquid to the first quantity of separated solid 229Th precipitate within the vessel to create a second suspension; storing the second suspension for a second period of time during which at least some of the first quantity of 229Th decays into 225Ac, forming a reduced second quantity of 229Th; and, separating the reduced second quantity of solid 229Th peroxide from at least some of the cover liquid solution of the second suspension to obtain a quantity of separated solid 229Th peroxide and a second liquid solution containing at least some 225Ac (after removal of the liquid fraction, a solid portion comprising a parent isotope can be used to generate additional quantities of decay product by repeated rounds of sequentially adding storage solution to the precipitate, and incubating the recovered precipitate from an additional in-growth period to generate additional decay product; [0037]).
Tranter focuses on embodiments where the 229Th precipitate is thorium iodate (e.g., [0025] and abstract), but also envisions other ion species capable of combining with 229Th (the parent isotope) to form a precipitate (precipitation can comprise using one or more ion species capable of combining with the parent isotope to form a precipitate; [0024)). Tranter additionally teaches that the storage solution should be capable of minimizing any dissolving of the precipitate while the daughter isotopes have increased solubility in the storage solution ([0033]).
Tranter does not specifically teach the precipitate being thorium peroxide, nor does Tranter teach the cover liquid solution comprising a NaNO3 solution of from 0.05 M to 1.0 M NaNO3 or maintaining the first suspension at a pH from 0.5 to 3 by the addition of a solution comprising KOH.
However, Robertson also teaches a method for generating solutions of actinium from a precipitate of thorium (formation of insoluble thorium peroxide while allowing the actinium isotopes to remain in solution; [0088]) and Robertson further teaches that the precipitate can be thorium iodate, the focus of Tranter, or thorium peroxide (the selective precipitant is hydrogen peroxide…in alternative embodiments, the selective precipitant is iodic acid…Hydrogen peroxide reacts with thorium ions to form insoluble thorium peroxide. … Iodic acid reacts with thorium ions to form insoluble thorium iodate; [0045]).
Therefore, it would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to replace the thorium-229 iodate precipitate in the method of Tranter with a thorium-229 peroxide precipitate, as taught by Robertson. One of ordinary skill in the art would have been motivated to do so because Tranter teaches that other precipitates can be used and Robertson teaches that thorium iodate and thorium peroxide can be used analogously as selective precipitates of thorium.
Regarding the limitations of without removing the solid 229Th precipitate from the vessel, while Tranter does not specifically use this phrasing, they do teach that “after removal of the liquid fraction, a solid portion comprising parent isotope can be used” ([0037]), which implies that the liquid fraction is the one being transferred from the vessel. This is further supported by the disclosure that in a related procedure “the supernatant can be removed from precipitation tank, by for example draining off the supernatant or by filtration, for example, cross-flow filtration” ([0049]) and that washing of the thorium is carried out by adding wash solution to the precipitation tank and subsequent removal of the wash solution from the precipitation tank ([0050]).
Thus, even if modified Tranter does not specifically teach separating the solid 229Th peroxide from the cover liquid without removing the solid 229Th precipitate from the vessel, it would have been obvious to one of ordinary skill in the art to do so. One of ordinary skill in the art would have found it obvious to do so because they would have been applying the known separation technique used elsewhere by Tranter for a nearly identical method of separating thorium-containing precipitate from a liquid solution to the separations of the solid thorium peroxide from the first suspension and from the second suspension.
Regarding the cover liquid solution comprising sodium nitrate, neither Tranter nor Robertson teach the cover liquid solution comprising NaNO3. However, Vasiliev teaches a 225Ac/213Bi generator where 225Ac is maintained in solution above a metal oxide sorbent material (conditions for high 213Bi affinity to the sorbent, while 225Ac remains in solution, makes the inorganic sorbents appropriate for use in an “inverse” generator…The sorbent [is] based on zirconium and yttrium mixed oxides; p. 1204, col. 1, ¶ 2). Vasiliev further teaches that the sorption of radionuclides to the metal oxide material decreases with increasing ionic strength of the solution (p. 1208, col. 1, ¶ 2) and that increasing the NaNO3 concentration to 1.0 M is effective at reducing 225Ac in the later-eluted 213Bi fractions (sorption from the initial solution containing 1 M NaNO3 … leads to drop down of actinium impurity by about an order of magnitude; p. 1208, col. 1, ¶ 3 and Figure 4a). The latter observation teaches that 1.0 M NaNO3 is effective at solubilizing 225Ac.
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to include in the cover liquid solution of modified Tranter NaNO3 at a concentration of 1.0 M, as taught by Vasiliev. One of ordinary skill in the art would have been motivated to do so in order to increase the ionic strength of the solution and thereby increase the elution of 225Ac from the thorium peroxide precipitate to which the 225Ac may otherwise adsorb, as it is closely related to metal oxides.
Regarding the pH of the first suspension, Abrão teaches maintaining the pH in solution above a precipitate of thorium peroxide in the range 2.0-2.5 in order to afford the complete precipitation of thorium peroxide (page 55, column 2, paragraph 1); i.e. Abrão teaches that a pH in the range of 2.0 to 2.5 minimizes the dissolving of the precipitate. The pH range of 2.0 to 2.5 taught by Abrão falls within the instantly claimed pH range of 0.5 to 3.
Abdellah also teaches a precipitate of thorium peroxide (Addition of H2O2 to Th4+ salts leads to precipitation of white thorium peroxide; p. 352, ¶ 1) and that the pH above the thorium peroxide precipitate can be controlled by adding NaOH (pH values were adjusted in the range from 1.5 to 3.5 using 20% NaOH; p. 352, ¶ 2).
Furthermore, it is well known in the art that potassium hydroxide (KOH) and sodium hydroxide (NaOH) are functionally equivalent bases that both can be added as pH adjusters in precipitation reactions. For example, Vaziri Hassas teaches a pH adjustment in the treatment of rare earth elements (sample’s pH is adjusted, and the sample is aged to form solid and liquid fractions, where the solid fraction comprises a precipitated salt; abstract) where the base can be one or more of NaOH, LiOH, KOH, NH3, or NH4OH (the pH adjustment …comprises adding a base…the base can comprise one or more of NaOH, LiOH, KOH, NH3, or NH4OH; [0078]).
Therefore, it would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to maintain the first suspension in the method of modified Tranter at a pH from 2.0-2.5, as taught by Abrão, by addition of a solution comprising KOH, as taught by Abdellah and Vaziri Hassas.
One of ordinary skill would have been motivated to maintain a pH of 2.0-2.5 because this pH minimizes the dissolving of the thorium peroxide precipitate, as taught by Abrão, a feature recognized as beneficial to the method of modified Tranter. One of ordinary skill in the art would have been further motivated to maintain the pH by addition of KOH because Abdellah teaches that pH in this range can be adjusted using NaOH, and KOH is a functional equivalent for the same purpose, as demonstrated by Vaziri Hassas. MPEP 2144.06(II).
Regarding claim 4, modified Tranter teaches the method of claim 1, where Tranter also teaches agitating the first suspension prior to separating the solid 229Th precipitate from the cover liquid solution (diffusion of decay product out of a crystal precipitate during the in-growth stage can be enhanced by agitation; [0035]).
Regarding claim 5, modified Tranter teaches the method of claim 1, and also teaches maintaining an excess of the precipitating agent in the cover liquid solution (an exemplary storage solution can comprise iodate…thorium iodate has very low solubility …in the presence of stochiometric excess of iodate; [0034]). Robertson also teaches maintaining an excess of hydrogen peroxide in a liquid solution above a thorium peroxide precipitate (paragraph 88, line 21).
One of ordinary skill in the art would have therefore found it obvious to maintain an excess amount of peroxide in the cover liquid solution when separating the first quantity and the second quantity of solid 229Th peroxide in the method of modified Tranter, as taught by both Tranter and Robertson. One of ordinary skill in the art would have been motivated to do so because both unmodified Tranter and the modifying reference of Robertson use an excess of precipitant in their related methods and doing so would be combining these teachings with predictable result of dissolving less thorium into solution.
Regarding claims 6-8, modified Tranter teaches the method of claim 5, and Robertson further teaches maintaining the excess amount of peroxide by adding 30% H2O2 solution prior to separating the solid thorium peroxide from the liquid solution (paragraph 88, lines 21-26, and Figure 13). The 30% H2O2 solution used by Robertson falls within the claimed ranges of weight percents H2O2 recited in both claims 7 and 8.
Therefore, it would have been obvious to one or ordinary skill in the art to maintain the excess peroxide in the cover liquid solution of modified Tranter by adding 30% H2O2 solution prior to the first suspension prior to separating the solid 229Th peroxide from the cover liquid solution, as taught by Robertson. One of ordinary skill would have been motivated to do so because they would be combining the teaching of Robertson that this is an appropriate reagent for maintaining excess peroxide with the method of modified Tranter that requires excess peroxide in the cover liquid solution.
Regarding claim 9, modified Tranter teaches the method of claim 1, and Robertson further teaches that thorium nitrate hydrate can be used in place of thorium metal in a method to provide thorium peroxide (paragraph 117 and 88). In particular, making the substitution in paragraph 88 of thorium nitrate tetrahydrate for the salts obtained from thorium metal, as taught by paragraph 117, Robertson teaches dissolving an amount of thorium nitrate tetrahydrate (Th(NO3)4.4H2O; [0117], line 10) in an acid solution to obtain a dissolved Th solution (dried salts are then redissolved in weak nitric acid; [0088], line 18). Robertson also teaches adding an amount of H2O2 to the dissolved Th solution thereby forming solid Th peroxide and a residual liquid phase ([0088], lines 19-23), and separating the solid Th peroxide from the residue liquid phase ([0088], line 24).
Regarding the acid solution comprising a NaNO3 solution from 0.05 M to 1.0 M, Vasiliev teaches that 1.0 M NaNO3 helps desorb 225Ac and other radionuclides from metal oxides, as analyzed above for claim 1, and it is the also the goal of Robertson and Tranter to leave 225Ac and other impurities in solution when preparing a thorium peroxide or iodate precipitate (Robertson [088], line 23; Tranter [0050]).
Therefore, it would have been obvious to one of ordinary skill in the art to further modify the method of modified Tranter to include thorium-229 peroxide synthesized by the method of Robertson and to include NaNO3 at 1.0 M in the acid solution, as taught by Vasiliev. One of ordinary skill in the art would have found it obvious to do so because they would have been combining prior art for the synthesis of thorium peroxide taught by Robertson with a method that required a source of thorium peroxide taught by modified Tranter. They would have been further motivated to include 1.0 M NaNO3 in the acid solution because this would help to remove radionuclide impurities from the thorium peroxide by increasing the ionic strength, as taught by Vasiliev.
Regarding claim 10, modified Tranter teaches the method of claim 1 where separating the first quantity of solid thorium peroxide from the cover liquid solution includes filtering ([0037]).
Regarding claim 15, modified Tranter teaches the method of claim 1 where first period of time is determined based upon the activity of the parent isotope and half-life of the daughter isotope, and suggests periods of 10-100 days ([0032] and Fig. 3), which includes the instantly claimed range of 25 days or less.
It is noted that the courts have stated where the claimed ranges “overlap or lie inside the ranges disclosed by the prior art” a prima facie case of obviousness exists (see In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976); In re Woodruff, 919 F.2d 1575, 16 USPQ2d 1934 (Fed. Cir. 1990); Titanium Metals Corp. of America v. Banner, 778 F2d 775. 227 USPQ 773 (Fed. Cir. 1985) (see MPEP 2144.05.01).
The courts have also found that “where the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation.” In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955). See MPEP 2144.05 II.
Therefore, the claimed ranges merely represent an obvious variant and/or routine optimization of the values of the cited prior art.
Regarding claim 21, modified Tranter teaches the method of claim 1, and also teaches agitating a first suspension prior to separating the solid 229Th precipitate from the cover liquid solution (diffusion of decay product out of a crystal precipitate during the in-growth stage can be enhanced by agitation; [0035]).
While Tranter does not specifically mention agitation in discussion of the second suspension (storage solution; [0037]), it would have been obvious to one of ordinary skill in the art to agitate the second suspension prior to separating the solid 229Th peroxide from at least some of the cover liquid solution of the second suspension, as required by claim 21. One of ordinary skill would have found this obvious because they would be applying the known technique of agitation to improve the isolation of decay products from the second suspension just as it was used for the first suspension. MPEP 2143(I)(C).
Regarding claim 22, modified Tranter teaches the method of claim 1, and also teaches maintaining an excess of the precipitating agent in the cover liquid solution (an exemplary storage solution can comprise iodate…thorium iodate has very low solubility …in the presence of stochiometric excess of iodate; [0034]). Robertson also teaches maintaining an excess of hydrogen peroxide in a liquid solution above a thorium peroxide precipitate (paragraph 88, line 21) and further teaches maintaining the excess amount of peroxide by adding an H2O2 solution prior to separating the solid 229Th peroxide from the liquid solution (paragraph 88, lines 21-26, and Figure 13).
Therefore, it would have been obvious to one or ordinary skill in the art to maintain the excess peroxide in the cover liquid solution of the second suspension in modified Tranter and to maintain the excess amount of peroxide in the cover liquid solution of the second suspension by adding an H2O2 solution to the second suspension to separating the solid 229Th peroxide from at least some of the cover liquid solution of the second suspension, as taught by Robertson. One of ordinary skill would have found it obvious to do so because they would be combining the teaching of Robertson that this is an appropriate reagent for maintaining excess peroxide with the method of modified Tranter that teaches excess precipitant in the cover liquid solution.
Regarding claim 23, modified Tranter teaches the method of claim 1, as analyzed above, but does not teach maintaining the second suspension at a pH from 0.5 to 3.
However, Abrão teaches maintaining the pH in solution above a precipitate of thorium peroxide in the range 2.0-2.5 in order to afford the complete precipitation of thorium peroxide (page 55, column 2, paragraph 1); i.e. Abrão teaches that a pH in the range of 2.0 to 2.5 minimizes the dissolving of the precipitate. The pH range of 2.0 to 2.5 taught by Abrão falls within the instantly claimed pH ranges of 0.5 to 3.
Abdellah also teaches a precipitate of thorium peroxide (Addition of H2O2 to Th4+ salts leads to precipitation of white thorium peroxide; p. 352, ¶ 1) and that the pH in such a reaction can be controlled by adding NaOH (pH values were adjusted in the range from 1.5 to 3.5 using 20% NaOH; p. 352, ¶ 2).
Furthermore, it is well known in the art that potassium hydroxide and sodium hydroxide are functionally equivalent bases that both can be added as pH adjusters in precipitation reactions. For example, Vaziri Hassas teaches a pH adjustment in the treatment of rare earth elements (sample’s pH is adjusted, and the sample is aged to form solid and liquid fractions, where the solid fraction comprises a precipitated salt; abstract) where the base can be one or more of NaOH, LiOH, KOH, NH3, or NH4OH (the pH adjustment …comprises adding a base…the base can comprise one or more of NaOH, LiOH, KOH, NH3, or NH4OH; [0078]).
Therefore, it would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to maintain the second suspension in the method of modified Tranter at a pH from 2.0-2.5, as taught by Abrão, by addition of a solution comprising KOH, as taught by Abdellah and Vaziri Hassas.
One of ordinary skill would have been motivated to maintain a pH of 2.0-2.5 because this pH minimizes the dissolving of the thorium peroxide precipitate, as taught by Abrão, a feature recognized as beneficial to the method of modified Tranter. One of ordinary skill in the art would have been further motivated to maintain the pH by addition of KOH because Abdellah teaches that pH’s in this range can be adjusted using NaOH, and KOH is a functional equivalent for the same purpose, as demonstrated by Vaziri Hassas. MPEP 2144.06(II).
Response to Arguments
Applicant's arguments filed 29 January 2026 have been fully considered but they are not persuasive.
Applicant argues, page 8, that because Vasiliev focuses on maintaining condition for selective affinity of 213Bi to the sorbent and not on selective precipitation or solubility that their teaching would not suggest a concentration range of 0.05 M to 1.0 M for NaNO3 in a cover solution for the method of modified Tranter.
However, Vasiliev specifically teaches “[p]roviding conditions for high 213Bi affinity to the sorbent, while 225Ac remains in solution.” Therefore, while Vasiliev is indeed focused on selective affinity for 213Bi, they also provide teachings on how to keep 225Ac in solution, which is of pertinence to the instantly claimed invention and the method of Tranter.
Applicant further argues that while Abrão teaches a pH range of 2.0-2.5, they do not suggest pH modification by addition of KOH in particular, or a base generally. However, it is well understood in the art that pH modification, and a pH increase in particular, is effected by addition of base, with KOH among the most common bases used for this purpose.
Furthermore, Abdellah is introduced to teach the addition of a base, NaOH, to modify the pH in a thorium peroxide precipitation reaction, and KOH is a well-known equivalent for the same purpose, as demonstrated by Vaziri Hassas. MPEP 2144.06(II).
Applicant’s arguments regarding the dependent claims, pages 9-10, rely upon the allowability of claim 1. Claim 1 being found obvious in view of the prior art, these claims were examined based upon their further limitations, as analyzed above.
Conclusion
Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to Nicholas A Piro whose telephone number is (571)272-6344. The examiner can normally be reached Mon-Fri, 8:00 am-5:00 pm.
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/NICHOLAS A. PIRO/Assistant Examiner, Art Unit 1738
/PAUL A WARTALOWICZ/Primary Examiner, Art Unit 1735