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Porous materials have been developed rapidly in recent years and have many particular properties due to their special geometries, such as lightweight, large specific surface area, good energy absorption and high heat-transfer capacity. A commonly used parameter to characterize porous structures is the number of pores per inch (PPI). In this work, PPI is computed in three-dimensional (3D) space rather than in two dimensions, for instance from a two-dimensional image. The studied structures are computer-generated or reconstructed from computed tomography (CT) scan images of real structures. The images segmented by the marker-based watershed algorithm (a part of the pore network model) are also used in this work. All the computations are conducted using the solver Parallel Algorithm for Crystal Evolution in 3D (Pace3D) for counting the number of pores accurately. The algorithm for counting the number of pores is proposed and modified according to the distribution of pores in different cases. This work is divided into three main stages: verifying the counting algorithm with an aligned structure, modifying it for complex structures, and applying it for real structures. The two modified algorithms are also validated by a periodic aligned structure, then two modified algorithms are used in complex structures to reduce the influence of periodic boundaries. The first modified algorithm is a subtraction of computed values and the second modified algorithm is an adjustment of the length of the measuring lines. The relationships between PPI and other important parameters, such as porosity, the total number of pores (Voronoi points) and strut radius, are observed. The effects of the stretching direction and degree of pores on PPI are also studied. The PPI of structures with different stretching factors in one or two directions is shown. In addition, the advantages and disadvantages of the two modified algorithms are also identified. By reconstructing the real structure and computing the PPI of the 3D models, the PPI of the real foams is found to be smaller than the value given by the manufacturer. This difference is particularly evident in the structure with a large PPI. By observing the PPI in different directions, it is possible to find the stretching of pores.

Lung cancer is the most common type of tumor, prone to contralateral lung, bone and brain metastasis. We report a 44-year-old woman diagnosed with lung cancer with multiple metastases in November 2015. Oral targeted drugs were initiated after the removal of brain metastases, and most lesions remained stable for 28 months. In March 2018, intracranial multiple metastases, as well as hydrocephalus accumulation in the third ventricle and lateral ventricles, and metastases in bone, adrenal gland, liver were noted. Hydrogen-gas monotherapy was started to control the tumor a month later. After 4 months, the size of multiple brain tumors was reduced significantly, and the amount of hydrocephalus in the third ventricle and lateral ventricles reduced significantly. After 1 year, all brain tumors had disappeared, and there were no significant changes in metastases in the liver and lung. These data show that, after standard treatments had failed, hydrogen-gas monotherapy elicited significant effective control of tumors (especially those in the brain), and survival time was lengthened.

Background Hydrogen therapy has been reported to convert exhausted programmed cell death receptor (PD-1)+CD8+ T cells to PD-1-CD8+ T cells, in advanced colorectal cancer patients, which is associated with significantly prolonged survival. Case presentation A 72-year-old female patient presented with metastatic gallbladder cancer and underwent symptomatic treatment combined with hydrogen therapy. The tumors were initially enlarged and displayed increased tumor marker expression following hydrogen inhalation therapy, after which they continued to remit, similar to the pseudo-progression that occurs after anti-PD-1 treatment. During one month of hydrogen therapy, the patient’s gallbladder and liver tumors continued to progress, and intestinal obstruction occurred. The intestinal obstruction was gradually relieved after symptomatic treatment, and the metastases in the abdominal cavity gradually decreased in size, anemia and hypoalbuminemia were corrected, and both the lymphocyte and tumor marker levels returned to normal. The patient was able to resume normal life two and a half months after hydrogen inhalation and survived over 10 months. Conclusion This is the first report of pseudo-progression followed by sustained remission after hydrogen inhalation. This phenomenon is similar to the pseudo-progression-remission pattern that occurs following PD-1 antibody treatment. These findings suggest that hydrogen may have an inhibitory effect on PD-1 expression.