Abstract: A diphenyl ether represented by the general formula (I), ##STR1## wherein R is a lower alkyl group having 1 to 4 carbon atoms, a lower alkoxyethyl group, the alkoxy substituent of which having 1 to 4 carbon atoms, or a lower alkoxyethoxyethyl group, the alkoxy substituent of which having 1 to 4 carbon atoms is capable of controlling annual and perennial weeds.

Abstract: A device for the fabrication of a concave diffraction grating wherein grating grooves are mechanically ruled on a spherical surface of a diffraction grating blank and wherein a tool for ruling the grating grooves is reciprocated along the spherical surface of the diffraction grating blank, guided by a cylindrical cam, to form grooves having a uniform sectional shape over their whole area, whereby a concave diffraction grating of high diffraction efficiency and little scattering light is fabricated.

Abstract: A tetrahydro-1,3,5-thiadiazin-4-one represented by the general formula, ##STR1## wherein R.sup.1, R.sup.2 and R.sup.3, which may be the same or different, represent each an alkyl group, allyl group, cycloalkyl group, alkoxyalkyl group, benzyl group, phenyl group or substituted phenyl group having as substituents alkyl groups, nitro group, halogen atoms, alkoxy groups, or trifluoromethyl group and R.sup.2 and R.sup.3 may also represent hydrogen atoms, is a new compound and useful for controlling insects and mites.

Abstract: N-(p-trifluoromethoxyphenyl)-3,4,5,6-tetrahydrophthalimide and N-(p-trifluoromethylthiophenyl)-3,4,5,6-tetrahydrophthalimide are capable of controlling annual and perennial weeds with high selectivity.

Abstract: O-Trifluoromethylbenzoic m'-isopropoxyanilide formed by the reaction between o-trifluoromethylbenzoic acid and m-isopropoxyaniline is very effective in controlling agricultural and horticultural plant diseases.

Abstract: An improved optical exposure apparatus for use in exposing a workpiece to a desired light pattern with a high alignment accuracy and a high operational speed is disclosed. The apparatus comprises a moving table on which a workpiece to be exposed is disposed, a movable holder on which a mask having an original pattern is disposed, a light source for irradiating said mask, a reduction lens for projecting a reduced pattern of said original pattern onto said workpiece, means for positioning said moving table to a predetermined position, means for detecting the error of said table positioning, means for calculating a value of the error of positioning the workpiece divided by the reduction rate of the reduction lens, and means for automatically shifting said movable holder by the calculated value so as to cancel said error.

Abstract: A tool for ruling grating grooves is reciprocated on a diffraction grating blank with the tool being restrained within a plane inclined at an arbitrary angle relative to a plane lying in contact with one point on a spherical concave of the diffraction grating blank. Translation for a variable pitch-groove spacing which changes as a function of the groove number or groove position is imparted to the diffraction grating blank in interlocking relationship with the reciprocation, thereby mechanically ruling the desired sphere of the grating blank with the grating grooves, whereby a concave diffraction grating which forms diffracted light of a specific wavelength into a completely stigmatic image at high diffraction efficiency can be manufactured.