Instead of expanding when heated — as is normally the case — the material contracts, a phenomenon known as negative thermal expansion.

与正常材料不同的是，当加热时，该材料不是膨胀，而是收缩，表现出负的热膨胀现象。

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Drax has biomass supply contracts in place but refuses to divulge where the material will come from, citing commercial confidentiality.

Drax目前已有生物质能供应合同，但其以商业机密为理由拒绝透露能源材料的来源。

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For example, the change in unit prices due to new labor contracts or material supplier's prices might be reflected in estimating future expenditures.

例如，由于新的劳动合同或材料价钱所引起的单元上的变更也可以在预测总成本中得以反映。

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Historically, he says, big tech services companies have worked more under time-and-material contracts, where clients reimburse them under hourly rates.

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Furthermore, independent risk research can hardly be conducted since the companies can block access to research material or ask the scientists to sign contracts where they agree not to publish anything that is not agreed with the company.

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By placing interleaved comb-like electrodes on the surface of lithium niobate, a material that is piezoelectric (and so expands or contracts as a current is passed through it), Dr Wixforth was able to fine-tune the waves to do his bidding.

ECONOMIST: Acoustic microfluidics