When Mohammad Hamedi Rad arrived in the US last year, he carried his Iranian passport, a hard-won student visa and a backpack containing $14,000 in hundred dollar-bills since there was no simpler way of getting money into the country.

"It was scary," Hamedi Rad, a chemical engineering graduate student at the University of Illinois at Urbana-Champaign, said of his late-night arrival in Chicago, where he declared the funds to airport customs officials. "I've never carried that much money before. I was extremely nervous."

Hamedi Rad's experience is by no means unheard of among many of the thousands of high-achieving, mostly middle-class Iranians studying in the US in increasing numbers despite US and international sanctions on Iran.

After gaining admission, they must navigate a way around sanctions on Iranian banks that make direct legal wire transfers to the West a practical impossibility, impeding the students' ability to pay tuition or transfer money for living expenses. Obtaining a US visa adds to the logistical hurdles and a depreciated Iranian rial means money can be tight.

The hardships facing Iranian students in the US and elsewhere were spotlighted after a clause aimed at aiding them appeared in a landmark deal struck last month between Iran and world powers on curbing its nuclear program.

Under the November 24 interim agreement, Iran agreed to halt its most sensitive nuclear activity in return for a six-month respite from some of the sanctions that have crippled its economy.

As part of the bargain, the US and its partners agreed to open up a channel between Iranian and foreign banks to enable "direct tuition payments to universities and colleges for Iranian students studying abroad" - in a deal that offers the potential for tangible help for Iranian students, authorizing $400 million in state assets frozen abroad to be used for tuition payments to foreign colleges and universities over the six-month period.

Precisely how and perhaps even whether that money will be spent is said to be discussed this week in Vienna, when Iran and major powers are thought to talk about implementing the accord.