Thanks to a reader for alerting me to a paper that was published last month on ResearchGate:
Title: “Progress Toward an Understanding of LENR-AHE Effects in Coated Constantan Wires in D2 Atmosphere: DC/AC Voltage Stimulation”
Authors: Francesco Celani, Georgio Vassallo
This paper presents a summary and some deeper details about the experiments presented at the 22nd International Conference on Condensed Matter Nuclear Science (ICCF22). It reports on the experimental study of LENR phenomena in Constantan (Cu55 Ni44 Mn1) from its inception in 2011 to the most recent experiments. Using an empirical approach we identified the effect of surface modification of the Constantan wires with coatings comprised of elements that enhance the absorption behavior, and oxides with low work function for electron emission. We also explored certain geometrical arrangements of the wires such as knots and coils in order to induce local thermal gradients and predictable hot-spots. Moreover, the DC polarization of the wires by a counter-electrode proved to be a versatile approach to induce non-equilibrium conditions that are essential for Anomalous Heat Effects (AHE), especially when a dielectric barrier discharge (DBD) is produced. From the review of experiments summarized in this article, we obtain indications that the main parameter controlling the AHE is the flux of reactive species through the surface of the loaded material. As a consequence, all other external conditions of the reactor core (voltage-current, temperature, pressure, electric field stimulations, DC and/or AC external fields), can be seen as co-factors that enable a flux of active species through surfaces and in the bulk of the materials. Although most of the tests are in agreement with a possible flux model, some results still lack an interpretation, probably due to limits of the experimental setup.
From the Conclusion section of the paper:
From the collected data the following conclusions can be drawn.
(a) The AHE occurrence is correlated with fast loading or unloading of the wire. In the case of unloading however, after a short time, the AHE vanishes.
(b) When loading/unloading occurs slowly, AHE is significantly reduced.
(c) A state of oscillation seems to be the most efficient since it produces AHE for a longer time with respect to fast loading or unloading (especially when a dielectric barrier discharge occurs).
(d) Loading and unloading occurrence, as assumed from R/R0 and variation in reactor pressure, strongly supportthe key role of deuterium flux (see  for a definition of flux).
There are additional external conditions, such as high temperature, low pressure, purity of the gas that facilitate the AHE