At the moment of / at the start of / in addition to (之际/之初/之余)

Structure Noun/clause + 之际 (at the moment of) ／之初 (at the start of) ／之余 (besides, after)

Three nominal closers with 之 (zhī) that frame something in time or circumstance, characteristic of formal prose. 之际 (zhī jì) = "at the moment of, on the occasion of": 值此新春之际 = "on the occasion of the New Year". 之初 (zhī chū) = "at the start of, in the early days of": 改革之初 = "in the early days of the reform". 之余 (zhī yú) = "besides, once done with": 工作之余 = "outside of work / after finishing work". All three turn what precedes into a temporal or circumstantial frame; they match the plainer 的时候 / 开始的时候 / 以外, but with a speech-or-essay tone.

Examples

值zhí此cǐ新xīn春chūn之zhī际jì，谨jǐn向xiàng各gè位wèi致zhì以yǐ诚chéng挚zhì的de祝zhù福fú。
On the occasion of the New Year, I extend my most sincere wishes to you all.
改gǎi革gé之zhī初chū，几jī乎hū无wú人rén看kàn好hǎo这zhè项xiàng政zhèng策cè。
In the early days of the reform, almost no one had faith in this policy.
工gōng作zuò之zhī余yú，他tā坚jiān持chí研yán读dú古gǔ典diǎn文wén学xué。
Outside of work, he keeps up his study of classical literature.
在zài民mín族zú危wēi亡wáng之zhī际jì，无wú数shù青qīng年nián挺tǐng身shēn而ér出chū。
At the moment the nation faced mortal peril, countless young people stepped forward.

Levels are indicative: they follow the standard Chinese Grammar Wiki (AllSet Learning) progression, not an official HSK 3.0 mapping. We never assign levels by eye.

This point and the other 370, with audio on every example, inside Wanyu.