Alternatives for schottky diode and transistor

[edmat]

I am creating a smoke alarm circuit (corresponding PDF is attached herewith). In the circuit diagram, Schottky diode MBR0530 and transistor ZTX451 have been shown to be used. They are not locally available where I reside. Can anyone suggest alternatives for the 2 devices which I can then search in the market?

 

[betwixt]

The ZTX451 can be almost any small signal type.
The diode type is not critical as it runs at low voltage and low current but it MUST be a Schottky type. In that application it needs to go into conduction then block the voltage very rapidly and a normal silicon diode will not be able to do that.

Brian.