Which of the following factors is NOT a bar to patentability?

The correct choice indicates that experimental results obtained after filing are not a bar to patentability. This stems from the understanding that once a patent application is filed, any subsequent experimental results or findings related to the initial invention do not contribute to the determination of whether the invention is patentable. The critical factor for patentability considers the state of the invention at the time of filing, including its novelty, non-obviousness, and usefulness.

In contrast, factors such as abandonment of the invention, prior public knowledge, and the publication of research results can affect patentability. Abandonment means that an inventor has shown a clear intent to discontinue the pursuit of a patent, which can preclude patent rights. Prior public knowledge refers to the invention being known or used publicly before the filing date, which can negate novelty. Similarly, the publication of research results before filing could also disclose the invention to the public, serving as a barrier to securing a patent by leading to a loss of novelty.

Thus, experimental results obtained after an application is filed do not interfere with the application’s patentability, highlighting the unique timing consideration associated with patent law.