He does not. He only gets injured due to a fight with arima due to stabs in both eyes causing him to have serious brain damage and lose his memory. They then take Kaneki to CCG and rename him to Haise and make him apart of them.
If you mean increasing the mass of the same gas in the same space, then pressure increases, because more particles are hitting the walls per second. If you mean replacing the particles with the same number of more massive ones, then there will be no effect on the pressure.
Millions of Christians do not observe Christmas. Among them are Quakers, Jehovah's Witnesses, and members of the Churches of Christ. Some of the half-dozen Christian faiths that do no celebrate Dec. 25 contend there is nothing in the Bible that says Christ was born on that day.