S evere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has rapidly spread globally and, as of May 2, 2020, had caused >3 million confirmed coronavirus disease cases (1). Although SARS-CoV-2 transmission through respiratory droplets and direct contact is clear, the potential for transmission through contact with surfaces or objects contaminated with SARS-CoV-2 is poorly understood (2). The virus can be detected on various surfaces in the contaminated environment from symptomatic and paucisymptomatic patients (3,4). Moreover, we recently reported detection of SARS-CoV-2 RNA on environmental surfaces of a symptomatic patient's household (5). Because SARS-CoV-2 remains viable and infectious from hours to days on surfaces (6,7), contact with a contaminated surface potentially could be a medium for virus transmission. In addition, high viral load in throat swab specimens at symptom onset (8,9) and peak infectiousness at 0-2 days for presymptomatic patients (8) suggest that presymptomatic patients may easily contaminate the environment. However, data are limited on environmental contamination of SARS-CoV-2 by patients who may be presymptomatic. Therefore, to test this hypothesis, we examined the presence of SARS-CoV-2 RNA in collected environmental surface swab specimens from 2 rooms of a centralized quarantine hotel where 2 presymptomatic patients had stayed. The Study Two Chinese students studying overseas returned to China on March 19 (patient A) and March 20 (patient B), 2020 (Table 1). On the day of their arrival in China, neither had fever or clinical symptoms, and they were transferred to a hotel for a 14-day quarantine. They had normal body temperatures (patient A, 36.3°C; patient B, 36.5°C) and no symptoms when they checked into the hotel. During the quarantine period, local medical staff were to monitor their body temperature and symptoms each morning and afternoon. On the morning of the second day of quarantine, they had no fever (patient A, 36.2°C; patient B, 36.7°C) or symptoms. At the same time their temperatures were taken, throat swab samples were collected; both tested positive for SARS-CoV-2 RNA by real-time reverse transcription PCR (rRT-PCR). The students were transferred to a local hospital for treatment. At admission, they remained presymptomatic, but nasopharyngeal swab, sputum, and fecal samples were positive for SARS-CoV-2 RNA with high viral loads (Table 1). In patient A, fever (37.5°C) and cough developed on day 2 of hospitalization, but his chest computed tomography images showed no significant abnormality during hospitalization. In patient B, fever (37.9°C) and cough developed on day 6 of

Aiming at the problem that the radiation monitoring system has high cost, big power consumption, and complex process of system constructing, a new wireless network radiation monitoring system is presented and implemented for radiation detection. This system adopts ZigBee technology and GPRS communication technology to realize the communication of real time data. Namely, this system uses ZigBee wireless protocol stack as control core, and adopts GPRS network as output transmission. Then build a FTP server to achieve the monitoring, statistics and alarm function of radiation dose.

Collaborative product design is a complex and time-consuming process whereby geographically distributed designers from different disciplines cooperate and collaborate. Well-studied collaborative product design system reduces development time and creates better products. This paper discusses the characteristics of collaborative product design based on multi-agent technology to minimize the development time, cost and risk. In particular, the proposed agents can provide the interaction spaces for coordinating the individual design activities. Furthermore, the mechanism of intercommunications between agents is discussed. This research work constitutes initial effort towards optimization of process of collaborative product design. Future effort will focus on the software implementation of the theory presented in this paper.

Prolyl 4-hydroxylase (P4H) is essential to maintain the stable triple-helix structure and function of human collagen 1(α) chain (COL3A1). To obtain hydroxylated human COL3A1, the human COL3A1 and the viral P4H A085R were co-expressed in P. pastoris GS115. The sequence of human COL3A1 without N-terminal and C-terminal was selected for expression. Colony PCR analysis and sequencing after transfection showed that the target gene had inserted successfully. Real-time quantitative PCR (RT-qPCR) indicated that human COL3A1 and P4H were expressed at the mRNA levels. SDS-PAGE and Western blotting analysis of supernatant from the recombinant methylotrophic yest culture showed that recombinant human COL3A1 (rhCOL3A1) was secreted into the culture medium with an apparent molecular mass of approximately 130 kDa. It was noted that the rhCOL3A1 expession quantity was higest at 120 h of induction. Furthermore, mass spectrometry analysis demonstrated that the rhCOL3A1 was expressed successfully. His-tagged rhCOL3A1 protein was purified by Ni-affinity column.