Abstract: A bat comprises a bat body and a foamed core member provided inside the inner space of the bat body. The foamed core member is made of pre-foamed methacryl resin beads, which have been treated with a foaming process. The pre-foamed methacryl resin is filled up in the bat body so that approximately 100% of the volume is filled up. The foamed core member is formed by heating the pre-foamed methacryl resin beads in order to perform a secondary foaming process while the inner space is sealed. The bat has an expanded sweet-spot area and enhanced impact absorbing characteristics. By leveling the thickness of the bat body, mechanical strength is enhanced, and further, the weight of the bat can be reduced and satisfactory swing balance can be obtained.

Abstract: Cyclopentenylheptanoic acid derivatives having the formula: ##STR1## wherein R is hydrogen or C.sub.1 to C.sub.4 alkyl and --(A)-- is: ##STR2## wherein M is hydrogen or triorganosilyl group, are prepared by reacting a compound having the formula: ##STR3## ps wherein X is halogen, with a compound having the formula: The derivatives belong to the pharmacologically-active class of compounds called "prostaglandins".

Abstract: A method for the manufacture of a heptanoic acid derivative represented by the formula ##STR1## wherein R.sup.3 stands for an acyloxy group, a halogen atom, or a hydrogen atom, which comprises reacting a cyclooctene derivative represented by the formula ##STR2## wherein Y stands for --R.sup.1, --COR.sup.1 or --SiR.sup.2.sub.3, wherein R.sup.1 is an alkyl group, an aryl group, or an aralkyl group and R.sup.2 is an alkyl group of 1 to 5 carbon atoms, with a compound represented by the formula ##STR3## wherein R.sup.3 has the same meaning as indicated above and X.sup.1 and X.sup.2 each is a halogen atom, is described along with uses for such compounds.