'in modern world' is correct and usable in written English.
For example, "In modern world, technology has greatly changed how we do things."
ART medicine is very much needed in modern world.
Automatic detection and track for infrared target is of great significance in modern world.
Raymond Jonas offers the first comprehensive account of this singular episode in modern world history.
A central phenomenon in modern world history is Western imperialism and its aftermath, decolonization.
Heterogeneous Network architectures plays a vital role in modern world communication that is virtually all communications and secret resource transactions are widely depending on the heterogeneous network architecture.
The workplace in modern world was not only for earning their lives but also for developing the quality of lives in knowledge-based society.
The changes that account for obesity in the modern world reside in the modern world, not in the relative constancy of human physiology.
In the modern world, an increasing proportion of the workforce is working indoors in offices.
In the modern world, that is unacceptable.
