Explain to me what the main subject of this article is:

"California officials are investigating the disappearance of 30 tons (61,000 pounds) of ammonium nitrate from a railcar crossing the Midwest. Ammonium nitrate, which is used as fertilizer, can also be used to create explosives and was a key component in the homemade bomb used in the 1995 attack on the Murrah Federal Building in Oklahoma City. The chemical was shipped by train from Cheyenne, Wyoming last month but when it arrived in the Mojave Desert two weeks later, its holding car was empty and the nitrate was gone. Dyno Nobel, the company responsible for shipping the ammonium nitrate is a leader in commercial explosives and filed a report with the federal National Response Center (NRC) on May 10 and an investigation is currently underway.

The Federal Railroad Administration, the California Public Utilities Commission, Union Pacific, and Dyno Nobel are looking into the disappearance, and the railcar is being transported back to Wyoming to undergo a thorough inspection. It is unclear how or when the chemical disappeared during transit, but Dyno Nobel told KQED News, “The railcar was sealed when it left the Cheyenne facility, and the seals were still intact when it arrived in Saltdale. The initial assessment is that a leak through the bottom gate on the railcar may have developed in transit.”
system
mujhe samajhaayen ki is lekh kaa mukhya vishay kya he:

"california ke adhikari midwest ko paar karne vaale ek railkar se ammonium nitrate ke 30 ton (61,000 pound) ke gaayab hone kii jaanch kar rahe hai. ammonium nitrate, jiskaa upyog urvarak ke rup main kiya jaataa he, kaa upyog visphotak banane ke liye bhi kiya ja saktaa he or homemed bam main ek pramukh ghatak tha.oklahoma city main murrah sangheey bhawan par 1995 ke hamale main. is rasayan ko pichley maheene cheyen, vyoming se train dwaara bhej diya gaya tha, lekin jab yah do saptaah baad mojaave registan main aayaa, to isaki holding car khaali thi or nitrate chalaa gaya tha. diano nobesemonium nitrate kii shipping ke liye jimmedaar company vanijyik visphotakon main ek netaa he or 10 may ko fedral neshnal rispance centre (enarasi) ke saath ek report daayar kii he or vartmaan main ek jaanch chal rahi he.

sangheey railmarg prashasan, california public utilities kamishan, union pacific or diano nobel gaayab hone main dekh rahe hai, or railkar ko puri tarah se nirikshan karne ke liye vyoming main waapas le jaaya ja rahaa he.yah spasht nahin he ki transit ke dauraan rasayan kaise yaa kab gaayab ho gaya, lekin diano nobel ne KQED news ko bataaya, “Cheyenne suvidha ko chhodane par railkar ko sil kar diya gaya tha, or saltdel main aane par sil abhi bhi barkaraar thi.praarambhik moolyankan yah he ki railkar par nichle get ke madhyam se ek risaav pargaman main viksit ho saktaa he. ”
user
is lekh main 30 ton ammonium nitrate ke gaayab hone main ek chal rahi jaanch shaamil he jise vioming se railkar dwaara mojaave registan tak le jaaya ja rahaa tha.jabaki mukhya rup se ek urvarak ke rup main upyog kiya jaataa he is padaarth kaa upyog ek visphotak ke rup main bhi kiya ja saktaa he jo suraksha chintaaon ko badhaata he.california public utilities kamishan sahit kai agenciyaan jaanch kar rahi hai.
assistant
<|system|>
</s>
<|user|>
mujhe samajhaayen ki is lekh kaa mukhya vishay kya he:

"california ke adhikari midwest ko paar karne vaale ek railkar se ammonium nitrate ke 30 ton (61,000 pound) ke gaayab hone kii jaanch kar rahe hai. ammonium nitrate, jiskaa upyog urvarak ke rup main kiya jaataa he, kaa upyog visphotak banane ke liye bhi kiya ja saktaa he or homemed bam main ek pramukh ghatak tha.oklahoma city main murrah sangheey bhawan par 1995 ke hamale main. is rasayan ko pichley maheene cheyen, vyoming se train dwaara bhej diya gaya tha, lekin jab yah do saptaah baad mojaave registan main aayaa, to isaki holding car khaali thi or nitrate chalaa gaya tha. diano nobesemonium nitrate kii shipping ke liye jimmedaar company vanijyik visphotakon main ek netaa he or 10 may ko fedral neshnal rispance centre (enarasi) ke saath ek report daayar kii he or vartmaan main ek jaanch chal rahi he.

sangheey railmarg prashasan, california public utilities kamishan, union pacific or diano nobel gaayab hone main dekh rahe hai, or railkar ko puri tarah se nirikshan karne ke liye vyoming main waapas le jaaya ja rahaa he.yah spasht nahin he ki transit ke dauraan rasayan kaise yaa kab gaayab ho gaya, lekin diano nobel ne KQED news ko bataaya, “Cheyenne suvidha ko chhodane par railkar ko sil kar diya gaya tha, or saltdel main aane par sil abhi bhi barkaraar thi.praarambhik moolyankan yah he ki railkar par nichle get ke madhyam se ek risaav pargaman main viksit ho saktaa he. ”</s>
<|assistant|>
is lekh main 30 ton ammonium nitrate ke gaayab hone main ek chal rahi jaanch shaamil he jise vioming se railkar dwaara mojaave registan tak le jaaya ja rahaa tha.jabaki mukhya rup se ek urvarak ke rup main upyog kiya jaataa he is padaarth kaa upyog ek visphotak ke rup main bhi kiya ja saktaa he jo suraksha chintaaon ko badhaata he.california public utilities kamishan sahit kai agenciyaan jaanch kar rahi hai.</s>
