The phrase "a first mode of" is correct and usable in written English.
It can be used when introducing or describing an initial method, approach, or way of doing something.
Example: "In our research, we identified a first mode of analysis that significantly improved our results."
Alternatives: "an initial method of" or "a primary approach to".
Musk dreamed up the Hyperloop in 2013, when considering a concept for a "fifth mode of transport".
"Social sharing", he asserts, represents "a third mode of organising economic production, alongside markets and the state".
According to Musk's blog post the Hyperloop could act as a fifth mode of mass transport after planes, trains, cars and boats.
Finally, we will show that our experimental set up has a second mode of operation named torsion induction magnetometer.
But there is a second mode of constitutional thought and argument, which we might call "small-c constitutionalism". This approach invokes constitutionalism in another, more literal sense.
He promised to unveil plans for a system that would whisk passengers from Los Angeles to San Francisco in half an hour, using a "fifth mode" of transportation — one that would supplement and perhaps even replace cars, boats, trains, and planes.
Although it is unclear if intracellular ATP in RPE fluctuates in response to light stimuli, activation of hBest1 through direct interaction provides a second mode of control for Ca2+-dependent Cl− currents by ATP in human RPE.
A second mode of operation that seems to have been popular and difficult to detect was used in the suicide car bombing of the United States Embassy in Beirut on April 18 , 1983
A second mode of thinking, Ma added, involves the integration of our abilities to analyze things and feel empathy for others, something he regards as being vital in almost any field of human endeavor — so that we can be both creative and disciplined, while remaining purposeful in our activities.
We were able to reveal a third mode of oxLDL-induced stress by showing with the help of a fluorescent, oxidizable lipid analogue (BODIPY™ 581/591 C11) that oxLDL-derived lipid peroxides and radicals migrate into cellular membranes giving rise to a chronic inoculation of the vascular cells with oxidative chain reactions.
