A Study on Microstructure and Properties of PHS Fiber Laser Welded Joints Obtained in Air Atmospheres.

Press-hardened steels (PHS) with a 1.5-mm-thick coated Al⁻Si layer is welded using an IPG YLS6000 continuous fiber laser in the air atmosphere. An SU5000 scanning electron microscope (SEM) and an Oxford EDS X-Max20 energy spectrometer are used to characterize the microstructure, which consists of delta (δ)-ferrite and lath martensite. It is similar to that of the welding performed in the Ar atmosphere, but the content of δ-ferrite is less. The reason is the formation of Al2O3 inclusions in the molten pool, which reacts with oxygen from the air ambient and the Al from the molten Al⁻Si coating of PHS. The oxygen content is measured with an ONH-3000 analyzer. An HV-1000 microhardness tester and DNS-100 universal material test equipment are performed to test the hardness and tensile strength. Similar hardness and strength of welded joints are achieved welding in the air atmosphere compared to that of the Ar atmosphere. Fracture was initialed in the fusion line of overlapping zone and propagated along the interface of two plates and fusion line due to the Al segregation.

Diversity and recombination of human parechovirus in children with acute gastroenteritis in Guangzhou, China.

Human parechovirus (HPeV), a member of Picornaviridae family, is a widespread pathogen causing a wide spectrum of diseases. Like other picornaviruses, HPeV genome recombination has been detected. A total of 322 fecal samples were collected from children outpatients in Guangzhou, China, including 42 (13.0%, 42/322) HPeV-positive samples detected in most of the infected children less than two years old. Seven HPeV genotypes (HPeV1, HPeV3, HPeV4, HPeV5, HPeV6, HPeV8 and HPeV14) were detected, among which, HPeV14, a rare genotype, was reported for the first time in children with acute gastroenteritis in China. This study revealed recombination events in eight samples. Clinical profiles did not yield statistical significance between children with HPeV infection alone and cases without pathogens detected. In conclusion, this study demonstrated that HPeV circulated in Guangzhou, China is diverse genetically, which provided evidence of recombination in HPeV in China.

[Associations of occupational safety atmosphere and behaviors with unintentional injuries].

OBJECTIVE: To evaluate the associations of perception of safety atmosphere at workplace, occupational safety attitude and behaviors with occupational unintentional injury among manufacturing workers. METHODS: A cross-sectional study was performed and a self-administered questionnaire was used to inquire socio-demographic characteristics, perceived safety atmosphere, occupational safety attitudes, occupational safety behaviors and occupational unintentional injuries among 10585 manufacturing workers selected from 46 enterprises in Guangdong. Structural equation modeling was applied to assess the relationship of the perception of safety atmosphere at workplace, occupational safety attitude, and occupational safety behaviors with occupational unintentional injury. RESULTS: Among 24 pathways supposed in structural equation model, 20 pathways (except for the attitude toward occupational safety, the attitude toward managers' support, the work posture and individual protection) were significantly related to the occupational unintentional injuries. The further analysis indicated that the perceived safety atmosphere might impact the occupational unintentional injuries by the attitude toward occupational safety and occupational safety behaviors. CONCLUSION: Workers' perception of safety atmosphere indirectly influenced on occupational unintentional injuries through occupational safety attitudes and occupational safety behaviors.