At present, the low degree of informatization in the construction industry chain is one of the prominent problems impeding the application efficiency of prefabrication. To break through the bottleneck of information integration and interaction in the construction process of prefabricated buildings, this paper proposes a conceptual framework of an Intelligent Construction System for Prefabricated Buildings based on the Internet of Things (ICSPB-IoT) according to the needs of government supervision departments, contractors and owners. Then this paper describes the formation of the “information network” from “information flow”, based on which the operating mechanism of the ICSPB-IoT is discussed using the method of system engineering analysis. Finally, the proposed ICSPB-IoT is graded into different implementation levels according to the degree of intelligence of the Internet of Things information, and the implementation path is proposed for construction enterprises with different levels of digitalization. The results show that the ICSPB-IoT provides cross-phase, cross-organizational information interaction for government supervision departments, contractors and owners to improve the efficiency of communication and collaboration between them. This paper also provides decision-making support for the design, layout and implementation of the Internet of Things for prefabrication construction enterprises.

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Streptomyces species possess strong secondary metabolism, the switches of which from the primary metabolism are complex and thus a challenge to holistically optimize their productivities. To avoid the complex switches and to reduce the limitations of different metabolic stages on the synthesis of metabolites, we designed a Streptomyces self-sustained system (StSS) that contains two functional modules, the primary metabolism module (PM) and the secondary metabolism module (SM). The PM includes endogenous housekeeping sigma factor σ hrdB and σ hrdB -dependent promoters, which are used to express target genes in the primary metabolism phase. SM consists of the expression cassette of σ hrdB under the control of a secondary metabolism promoter, which maintains continuous activity of the σ hrdB -dependent promoters in the secondary metabolism phase. As a proof-of-principle, the StSS was used to boost the production of some non-toxic metabolites, including indigoidine, undecylprodigiosin (UDP), ergothioneine, and avermectin, in Streptomyces. All these metabolites can undergo a continuous production process spanning the primary and secondary metabolism stages instead of being limited to a specific stage. Scale-up of UDP fermentation in a 4 L fermentor indicated that the StSS is a stable and robust system, the titer of which was enhanced to 1.1 g/L, the highest at present. This study demonstrated that the StSS is a simple but powerful strategy to rationally engineer Streptomyces cell factories for the efficient production of non-toxic metabolites via reconstructing the relationships between primary and secondary metabolism.

This paper surveys recent work in several photodetector areas including high-speed, low-noise avalanche photodiodes, high-power photodiodes, solar-blind ultra-violet PIN photodiodes, and quantum dot infrared photodetectors (QDIPs).

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