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 .
This action is responsive to Applicant’s amendment/remarks filed 29 June 2026.
The rejection of claims 1 and 7 under 35 U.S.C. 103 as being unpatentable over Oldenburg (US-20160250612-A1) is withdrawn in view of the above amendments.
The rejection of claims 2 and 4-6 under 35 U.S.C. 103 as being unpatentable over de Oldenburg (US-20160250612-A1) in view of Calderon et al. (“Review of solid particle materials for heat transfer fluid and thermal energy storage in solar thermal power plants”) is withdrawn in view of the above amendments.
The double patenting rejection of is maintained in view of the above amendments/arguments.
The following rejections and/or objections are either reiterated or newly applied.
They constitute the complete set presently being applied to the instant application.
Continued Examination Under 37 CFR 1.114
A request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e), was filed in this application after final rejection. Since this application is eligible for continued examination under 37 CFR 1.114, and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114. Applicant's submission filed on 27 April 2026 has been entered.
Response to Amendments & Arguments
Applicant’s arguments with respect to claims 1-2 and 4-7 have been considered but are moot because the arguments do not apply to all the references being used in the current rejection. Arguments against Calderon are moot due to the new grounds of rejection necessitated by amendment. The current rejection utilizes new references, Suresh et al. (US-20140116949-A1) in view of Calderon et al. (“Review of solid particle materials for heat transfer fluid and thermal energy storage in solar thermal power plants”) under new ground(s) of rejection which renders obvious the instant claims.
Applicant argues Calderon et al. does not provide a basis of zero-valent iron coating (see page 9).
In response, Applicant’s arguments are acknowledged but are not persuasive. Suresh et al. teaches absorbent individual particles comprising a carrier coated with nanoparticles of zerovalent iron (ZVI hereinafter) (para. [0007]). Suitable carriers— which correspond to the claimed core—include silica gel, diatomite, fly-ash, and rice husk ash (para [0010]). These disclosures read on the claimed invention. Suresh et al. further highlights that these particles are environmentally friendly, relatively inexpensive, and less complex than many current nanoparticles—typically used to remove heavy metals from aqueous streams (para [0019]).
Calderon et al. teaches a solid particle material for heat transfer and thermal energy storage systems, particularly in solar thermal power plants applications (Abstract); wherein such solid particles (e.g. silica sand, fly ash, metal oxides, Table 9) are advantageous due to their thermal stability under high-temperature conditions, energy storage capability, and cost-effectiveness. The particles are flowing through the receiver, capturing (i.e., absorbing) the concentrated sunlight (Introduction, page 2).
The cited references collectively teach the same constituent materials (i.e., silica, fly ash, and metal oxides) to form a particle. Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filling date of the claimed invention to expect particles with similar compositions to exhibit comparable functionalities. The expectation is driven by the shared focus on absorptivity. As such, when combined with general knowledge in the art, render the claimed zero-valent iron coating obvious.
Applicant argues Calderon et al. teaches impurities within the natural silica are strictly in the form of iron oxides (hematite, magnetite) (see page 10), thereby failing to provide a basis for zero-valent iron to achieve a maximized solar absorption of over 92%.
In response, Applicant’s arguments are acknowledged but are not persuasive. As stated above, Suresh et al. in combination of Calderon et al. read on the zero-valent iron coating.
Calderon et al. teaches that material absorptance is defined by the proportion of light absorbed to a black body, which varies by radiation source (3.1 Receiver thermal efficiency, page 7). Calderon et al. further teaches that oxidation induces color changes and achieving a mean solar absorptance exceeding 90% when the material appears black as in Figure 3 (3.1 Receiver thermal efficiency page 9, Figure 3). The disclosure of solar absorptance exceeding 90% reads on and encompasses the Applicant’s argued threshold of over 90%.
Furthermore, Calderon et al. emphasizes that the optical radiative properties of the particle media is crucial to overall efficiency, as sub-optimal solar absorptance or essive emissivity can increase thermal losses (3.1 Receiver thermal efficiency).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filling date of the claimed invention to incorporate the particles of Suresh et al. to a solar power system taught by Calderon et al. The person having ordinary skill in the art would expect such application would yield predictable results, specifically as the references collectively teach similar particles comprise of analogous materials. Consequently, this combination would optimize the absorption functionality described by Calderon allowing a practitioner to effectively control optical radiative properties, solar absorptance, and emissivity.
Applicant argues the method of making the particle (see page 10).
In response, Applicant’s arguments are acknowledged but are not persuasive. The pending claims are drawn to a product rather than the method. Furthermore, Applicant’s election of Group I (the particle for heat transfer) without traverse was acknowledged on 02 December 2025 and made final.
Claim Rejections - 35 USC § 112
The following is a quotation of 35 U.S.C. 112(b):
(b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention.
The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph:
The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention.
Claims 4 and 7 rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second
paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor (or for applications subject to pre-AIA 35 U.S.C.
112, the applicant), regards as the invention.
With regard to claim 4, the limitation "metal oxide" has been deleted from claim 1 which its dependent on. As such, there is insufficient antecedent basis for this limitation in the claim. The limitation of “metal oxide” at 5 to 10 parts by weight based on 100 parts by weight of the silica remains under consideration and will be applied to any embodiment of the invention.
With regard to claim 7, the applicant states “wherein the particle for heat transfer or heat storage is comprised in heat transfer” is indefinite. The claim merely states that the particle is comprised “in” heat transfer, which is a process rather than a physical structure. This fails to define a structural limitation.
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.
Claim 1 is rejected under 35 U.S.C. 103 as being unpatentable over Suresh et al. (US-20140116949-A1).
With regard to claim 1, Suresh et al. teaches individual particles comprising a carrier coated with nanoparticles of zerovalent iron (ZVI hereinafter) (para. [0007]). Suitable carriers— which correspond to the claimed core—include silica gel, diatomite, fly-ash, and rice husk ash (para [0010]).
Suresh et al. does not explicitly teach the carrier is pure silica. However, Suresh et al. teaches diatomite, rice husk ash, and fly ash are predominately silica-based, structurally establishing that the core comprises silica. Specifically, the preferred carrier, diatomite, contains 80-90 wt.% silica, and 2-4 wt.% alumina, and 0.5-2wt.% iron oxide, while rice husk ash is comprised primarily of 80-90% activated silica and 5-10% activated carbon (para [0029]).
With regard to the core, one having ordinary skill in the art would have a reasonable expectation that diatomite and rice husk ash containing more than 80 wt.% of silica would offer silica in the core. As such, it would have been obvious prior to the effective filling date of the claimed invention that silica can be found within the core. Therefore, the invention as a whole would be obvious to a person of ordinary skill in the art.
Please note, the intended use of the above claimed composition (i.e. for heat transfer or heat storage) does not patentably distinguish the composition, per se, since such undisclosed use is inherent in the reference composition. In order to be limiting, the intended use must create a structural difference between the claimed composition and the prior art composition.
In the instant case, the intended use does not create a structural difference, thus the intended use is not limiting (see, e.g., MPEP 2112).
Claims 2, 4-7, and 11-13 are rejected under 35 U.S.C. 103 as being unpatentable over Suresh et al. (US-20140116949-A1) as applied to claim 1 above, and further in view of Calderon et al. (“Review of solid particle materials for heat transfer fluid and thermal energy storage in solar thermal power plants”, located in Information Disclosure Statement).
The teachings of Suresh et al. is discussed above.
With regard to claim 2, Suresh et al. does not explicitly teach the use of silica in the form of sand. However, Suresh et al. does teach the use of any porous material and various silica-based materials—such as silica gel, fly ash, rice husk ash, and diatomite (para [0023]). Suresh et al. further notes that diatomite can be calcined and contain crystallized silica (which silica sand is predominately comprised of)(para [0021]).
In the same field of endeavor, Calderon et al. teaches a solid particle material for heat transfer and thermal energy storage systems, particularly in solar thermal power plants applications (Abstract); wherein such solid particles (e.g. silica sand, metal oxides, Table 9) are advantageous due to their thermal stability under high-temperature conditions, energy storage capability, and cost-effectiveness (Introduction, page 2). Calderon et al. explicitly identifies silica sand as a preferred storage medium due to its natural abundance, chemically inert material with a favorable thermal energy storage (TES hereinafter) capacity, and thermal stability (3.2 TES Capacity).
With regard to the silica sand, it would have been obvious to one of ordinary skill in the art before the effective filling date of the claimed invention to modify Suresh et al.’s silica containing particles to adopt the form of silica sand. The cited references collectively teach a predominately silica concentration, however, in different physical forms. The person having ordinary skill in the art would expect such modification to yield predictable results while enhancing material versatility and applicability in thermal systems consistent with Calderon’s teaching.
With regard to claim 4, Suresh et al. does not teach within the claimed concentration ratio of coating to silica. However, Suresh et al. teaches a preferred carrier comprising diatomite consists of 80-90 wt.% silica, and 2-4 wt.% alumina, and 0.5-2wt.% iron oxide. This composition reads on the claimed weight range within metal oxide to silica.
With regard to claim 5, Suresh et al. a diatomite particle size distribution between about 10 to 200 µm (para [0021]), and a nZVI particle size have a particle size ranging from about 35 nm to 75 nm (0.010 to 0.075 µm)(para [0038]). While Suresh et al. does not explicitly teach the overall size of the entire particle, these disclosures, if combined, fall within the claimed range as the total particle size would range from 10.01 to 200.075 µm.
In the same field of endeavor, Calderon et al. teaches particle sizes ranging from 200 to 1000 µm (2.1 Solid particles receiver, page 5, Table 1), which overlaps the claimed range. Calderon et al. further teaches that particle flow dynamics are significantly influenced by particle size, noting that excessively small particles diminish solar receiver efficiency, while large particles present fluidization challenges (2.1 Solid particles receiver, page 5). Calderon et al. also states that particle size has little influence in the storage, but it holds substantial influence over heat transfer performance in both direct receivers and HEX systems; smaller particle enhance heat exchange performance, but a limit exists for fluidized heat exchange to maintain the desired heat transfer coefficient (HEX efficiency, page 12).
With regard to the particle size, it would have been obvious to one of ordinary skill in the art before the effective filling date of the claimed invention to adjust the particle size in Suresh et al. by adopting the larger particle size range taught by Calderon. The person having ordinary skill in the art would expect such modification would yield predictable results to optimizing both thermal storage and fluidity within the thermal energy storage system.
With regard to claim 6, Suresh et al. does not teach the roundness and sphericity of the particles.
In the same field of endeavor, Calderon et al. teaches particles with a roundness and sphericity both of 0.9 (Table 1), which is falls in the claimed range. Specifically, Calderon et al. teaches that the roundness and sphericity are essential for mitigating erosion damage within the system, noting that proppants characterized by high sphericity and roundness exhibit superior absorptance and durability. Such particles are identified as ideal for use in solid particle receivers because they maintain structural integrity and functional utility under operational stress (3.4 Erosion evaluation).
With regard to the roundness, it would have been obvious to one of ordinary skill in the art before the effective filling date of the claimed invention to adjust the particles of Suresh et al. to incorporate the roundness and sphericity specifications taught by Calderon. The person having ordinary skill in the art would expect such modification would yield predictable results, specifically enhancing thermal storage performance and particle fluidity while reducing system erosion, thereby achieving the optimized functionality described by Calderon.
With regard to claim 7, Suresh et al. does not teach the particle is comprised in a heat transfer for a concentrating solar power system.
In the same field of endeavor, Calderon et al. teaches the use of solid particles as thermal energy storage (TES) and heat transfer fluid material. Specifically, Calderon et al. teaches a system in which particles fall through a beam of concentrated radiation in a concentrated solar power (CSP) solar tower system (Introduction, page 2), which reads on the claimed particle for heat transfer comprised in a concentrating solar power system. Calderon et al. further notes the primary advantages of these particle-based storage media include chemically inert, thermal stability exceeding 1100 C, high energy storage density, and relatively low material costs (Introduction, page 2).
With regard to the particle application, it would have been obvious to one of ordinary skill in the art before the effective filling date of the claimed invention to incorporate the particles of Suresh et al. to a solar power system taught by Calderon et al. The person having ordinary skill in the art would expect such application would yield predictable results, specifically as the references collectively teach similar particles comprising comparable components, thereby achieving the optimized functionality described by Calderon.
With regard to claim 11, Suresh et al. does not explicitly teach the particle color or solar light absorption.
In the same field of endeavor, Calderon et al. teaches that material absorptance is defined by the proportion of light absorbed to a black body, which varies depending on the radiation source (3.1 Receiver thermal efficiency, page 7).
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Calderon et al. further demonstrates that oxidation induces color changes, achieving a mean solar absorptance exceeding 90% when the material appears black as in Figure 3 (3.1 Receiver thermal efficiency page 9, Figure 3).
Furthermore, Calderon et al. emphasizes that the optical radiative properties of the particle media is crucial to overall efficiency, as sub-optimal solar absorptance or essive emissivity can increase thermal losses (3.1 Receiver thermal efficiency).
With regard to the absorptivity, it would have been obvious to one of ordinary skill in the art before the effective filling date of the claimed invention to incorporate the particles of Suresh et al. to a solar power system taught by Calderon et al. The person having ordinary skill in the art would expect such application would yield predictable results, specifically as the references collectively teach similar particles comprise of analogous materials. Consequently, this combination would optimize the absorption functionality described by Calderon allowing a practitioner to effectively control optical radiative properties, solar absorptance, and emissivity.
With regard to claim 12, as stated above, Suresh et al. a diatomite particle size distribution between about 10 to 200 µm (para [0021]), and a nZVI particle size have a particle size ranging from about 35 nm to 75 nm (0.010 to 0.075 µm)(para [0038]). While Suresh et al. does not explicitly teach the overall size of the entire particle, these disclosures, if combined, fall within the claimed range as the total particle size would range from 10.01 to 200.075 µm. While Suresh et al. does not explicitly teach the overall size of the entire particle, these disclosures, if combined, fall within the claimed range as the total particle size would range from 10.01 to 200.075 µm.
In the same field of endeavor, Calderon et al. teaches the optimal particle size of 160 to 504 µm for heat exchange efficiency and roundness and sphericity of 0.9 (which overlaps the claimed ranges, 2.1 Solid particles receiver, page 5, Table 1). Calderon et al. further teaches that particle flow dynamics are significantly influenced by particle size, noting that excessively small particles diminish solar receiver efficiency, while large particles present fluidization challenges (2.1 Solid particles receiver, page 5). Calderon et al. also states that particle size has little influence in the storage, but it holds substantial influence over heat transfer performance in both direct receivers and HEX systems; smaller particle enhance heat exchange performance, but a limit exists for fluidized heat exchange to maintain the desired heat transfer coefficient (HEX efficiency, page 12).
Furthermore, Calderon et al teaches that the roundness and sphericity are essential for mitigating erosion damage within the system, noting that proppants characterized by high sphericity and roundness exhibit superior absorptance and durability. Such particles are identified as ideal for use in solid particle receivers because they maintain structural integrity and functional utility under operational stress (3.4 Erosion evaluation).
As stated above, Suresh et al. and Calderon et al. in combination teach the claimed properties (size and roundness/sphericity) of the particle.
With regard to claim 13, Suresh et al. does not explicitly teach the thermal conductivity of the particle.
In the same field of endeavor, Calderon et al. teaches that suitable solid particles exhibit a thermal conductivity is 0.5 to 2 W/mK (Table 1). Calderon et al. further teaches that this thermal conductivity is a function of heat exchange and surface area parameters (e.g. thickness, mass, and porosity), rather than relying on particle durability (3.3 HEX efficiency page 12).
With regard to the thermal conductivity, it would have been obvious to one of ordinary skill in the art before the effective filling date of the claimed invention to integrate the particles of Suresh et al. to a solar power system taught by Calderon et al. The person having ordinary skill in the art would expect such application would yield predictable results, as both references collectively teach similar particles and components, thereby permitting the optimization of the surface area functionalities described by Calderon required to achieve the desired thermal conductivity.
Double Patenting
The nonstatutory double patenting rejection is based on a judicially created doctrine grounded in public policy (a policy reflected in the statute) so as to prevent the unjustified or improper timewise extension of the “right to exclude” granted by a patent and to prevent possible harassment by multiple assignees. A nonstatutory double patenting rejection is appropriate where the conflicting claims are not identical, but at least one examined application claim is not patentably distinct from the reference claim(s) because the examined application claim is either anticipated by, or would have been obvious over, the reference claim(s). See, e.g., In re Berg, 140 F.3d 1428, 46 USPQ2d 1226 (Fed. Cir. 1998); In re Goodman, 11 F.3d 1046, 29 USPQ2d 2010 (Fed. Cir. 1993); In re Longi, 759 F.2d 887, 225 USPQ 645 (Fed. Cir. 1985); In re Van Ornum, 686 F.2d 937, 214 USPQ 761 (CCPA 1982); In re Vogel, 422 F.2d 438, 164 USPQ 619 (CCPA 1970); In re Thorington, 418 F.2d 528, 163 USPQ 644 (CCPA 1969).
A timely filed terminal disclaimer in compliance with 37 CFR 1.321(c) or 1.321(d) may be used to overcome an actual or provisional rejection based on nonstatutory double patenting provided the reference application or patent either is shown to be commonly owned with the examined application, or claims an invention made as a result of activities undertaken within the scope of a joint research agreement. See MPEP § 717.02 for applications subject to examination under the first inventor to file provisions of the AIA as explained in MPEP § 2159. See MPEP § 2146 et seq. for applications not subject to examination under the first inventor to file provisions of the AIA . A terminal disclaimer must be signed in compliance with 37 CFR 1.321(b).
The filing of a terminal disclaimer by itself is not a complete reply to a nonstatutory double patenting (NSDP) rejection. A complete reply requires that the terminal disclaimer be accompanied by a reply requesting reconsideration of the prior Office action. Even where the NSDP rejection is provisional the reply must be complete. See MPEP § 804, subsection I.B.1. For a reply to a non-final Office action, see 37 CFR 1.111(a). For a reply to final Office action, see 37 CFR 1.113(c). A request for reconsideration while not provided for in 37 CFR 1.113(c) may be filed after final for consideration. See MPEP §§ 706.07(e) and 714.13.
The USPTO Internet website contains terminal disclaimer forms which may be used. Please visit www.uspto.gov/patent/patents-forms. The actual filing date of the application in which the form is filed determines what form (e.g., PTO/SB/25, PTO/SB/26, PTO/AIA /25, or PTO/AIA /26) should be used. A web-based eTerminal Disclaimer may be filled out completely online using web-screens. An eTerminal Disclaimer that meets all requirements is auto-processed and approved immediately upon submission. For more information about eTerminal Disclaimers, refer to www.uspto.gov/patents/apply/applying-online/eterminal-disclaimer.
Claims 1-2 and 4-7 and 11-13 provisionally rejected on the ground of nonstatutory double patenting as being unpatentable over claim 1 and 5 of copending Application No. 18/531541 (reference application) is maintained. Although the claims at issue are not identical, they are not patentably distinct from each other because of the reasons listed below.
US Application No. 18/531541 claims a thermal transfer media for a concentrating solar system comprising: a core of silica sand and a coating containing iron oxide. The particle size of the thermal transfer media is 100μm to 1000μm. US 18/168613 claims overlap in components and particle size used as the instant claims. The difference between the instant claims lies in the fact that ‘541 claims includes the specific inclusion of specific coating to the thermal transfer. A person of ordinary skill in the art would conclude that the invention described in the instant claims would have been an obvious variation. This is a provisional nonstatutory double patenting rejection because the patentably indistinct claims have not in fact been patented.
Conclusion
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/A.A.W./Examiner, Art Unit 1761
/ANGELA C BROWN-PETTIGREW/Supervisory Patent Examiner, Art Unit 1761
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