Abstract: The main purpose of the invention is to provide a novel pyridine derivative or a pharmaceutically acceptable salt thereof. Examples of the invention include a pyridine derivative represented by general formula [1], and a pharmaceutically acceptable salt thereof. This compound or a pharmaceutically acceptable salt thereof exhibits mGluR5 inhibitory activity, and can therefore be used as an agent for the prevention or treatment of, e.g., pain (for example, acute pain, chronic pain, inflammatory pain, neuropathic pain, hyperalgesia, thermal hyperalgesia, allodynia, pain due to noxious thermal stimulation, pain due to noxious mechanical stimulation, pain in the lower urinary tract or reproductive organs, or migraine), pruritus, lower urinary tract symptoms or lower urinary tract dysfunctions, gastroesophageal reflux disease (GERD), gastroesophageal reflux associated with transient lower esophageal sphincter relaxation (TLESR), and diseases of the central nervous system.

Abstract: A main object of the invention is to provide a novel useful vitamin D3 derivative, which has an excellent vitamin D3 activity and, as compared with conventional vitamin D3 derivatives, has a relatively small amount of influence on the systemic calcium metabolism. The invention includes a 9,10-secopregnane derivative of the following general formula [1] and a pharmaceutical composition containing it as active ingredient. In the general formula [1], the following partial structure between the 16-position and the 17-position means a single bond or a double bond: Y is a single bond, an alkylene, an alkenylene or phenylene; R1 and R2 are the same or different, each represents hydrogen, an alkyl or a cycloalkyl; or R1 and R2, taken together with the adjacent carbon atom, form a cycloalkyl; R3 is hydrogen or methyl; Z is hydrogen, hydroxy or —NR11R12.

Abstract: A main object of the invention is to provide a novel useful vitamin D3 derivative, which has an excellent vitamin D3 activity and, as compared with conventional vitamin D3 derivatives, has a relatively small amount of influence on the systemic calcium metabolism. The invention includes a 9,10-secopregnane derivative of the following general formula [1] and a pharmaceutical composition containing it as active ingredient. In the general formula [1], the following partial structure between the 16-position and the 17-position means a single bond or a double bond: Y is a single bond, an alkylene, an alkenylene or phenylene; R1 and R2 are the same or different, each represents hydrogen, an alkyl or a cycloalkyl; or R1 and R2, taken together with the adjacent carbon atom, form a cycloalkyl; R3 is hydrogen or methyl; Z is hydrogen, hydroxy or —NR11R12.

Abstract: In a method of biologically removing nitrogen and a system therefor according to the present invention, by utilizing the characteristics of AH bacteria as being nitrifying bacteria of nitrous acid type for displaying high activity at the high concentration of ammonium nitrogen and the characteristics of AL bacteria as being nitrifying bacteria of nitrous acid type for displaying high activity at the low concentration of the ammonium nitrogen, in the nitrifying process, operations capable of obtaining the maximum nitrifying speed in accordance with the concentration of the ammonium nitrogen can be performed, and the nitrifying reaction of nitrous acid type for producing nitrous acid as being an intermediate oxide material of the ammonium nitrogen can be performed.

Abstract: In a method of biologically removing nitrogen and a system therefor according to the present invention, by utilizing the characteristics of AH bacteria as being nitrifying bacteria of nitrous acid type for displaying high activity at the high concentration of ammonium nitrogen and the characteristics of AL bacteria as being nitrifying bacteria of nitrous acid type for displaying high activity at the low concentration of the ammonium nitrogen, in the nitrifying process, operations capable of obtaining the maximum nitrifying speed in accordance with the concentration of the ammonium nitrogen can be performed, and the nitrifying reaction of nitrous acid type for producing nitrous acid as being an intermediate oxide material of the ammonium nitrogen can be performed.

Abstract: In a method of biologically removing nitrogen and a system therefor according to the present invention, by utilizing the characteristics of AH bacteria as being nitrifying bacteria of nitrous acid type for displaying high activity at the high concentration of ammonium nitrogen and the characteristics of AL bacteria as being nitrifying bacteria of nitrous acid type for displaying high activity at the low concentration of the ammonium nitrogen, in the nitrifying process, operations capable of obtaining the maximum nitrifying speed in accordance with the concentration of the ammonium nitrogen can be performed, and the nitrifying reaction of nitrous acid type for producing nitrous acid as being an intermediate oxide material of the ammonium nitrogen can be performed.

Abstract: In a method of biologically removing nitrogen and a system therefor according to the present invention, by utilizing the characteristics of AH bacteria as being nitrifying bacteria of nitrous acid type for displaying high activity at the high concentration of ammonium nitrogen and the characteristics of AL bacteria as being nitrifying bacteria of nitrous acid type for displaying high activity at the low concentration of the ammonium nitrogen, in the nitrifying process, operations capable of obtaining the maximum nitrifying speed in accordance with the concentration of the ammonium nitrogen can be performed, and the nitrifying reaction of nitrous acid type for producing nitrous acid as being an intermediate oxide material of the ammonium nitrogen can be performed.