Research progress of residual stress measurement methods.

Residual stress refers to self-equilibrating stress present within materials, with the potential to significantly affect manufacturing processes and performance. Therefore, accurately and quantitatively measuring residual stress is always of great importance. This study provides a comprehensive review of various characterization techniques for residual stress, including their principles, development history, applications, and limitations. Initially, several destructive techniques such as the hole-drilling method, ring-core method, deep hole drilling method, slitting method, and contour method are summarized. Subsequently, three nondestructive techniques based on X-ray/electron diffraction, magnetic signals, and ultrasonic signals are evaluated. In the final part of this overview, special attention is given to a newly-developed technique for measuring residual stress, which combines incremental focused ion beam (FIB) milling and digital image correlation (DIC). Our review aims to guide further investigations on residual stress and identify the future development of techniques for measuring residual stress.

Self-healing, antibacterial, and conductive double network hydrogel for strain sensors.

Multifunctional hydrogels have great potential in smart wearable technology, flexible electronic devices, and biomedical research. However, it is highly challenging to prepare unique conductive hydrogels with combined properties such as self-healing, self-adhesive, and antibacterial activity. In this regard, herein, a conductive double network hydrogel (ACBt-PAA/CMCs) was fabricated using carboxymethyl chitosan (CMCs), acrylic acid (AA), and alkaline calcium bentonite (ACBt) via a convenient approach. Owing to the hydrogen bond interaction between PAA and CMCs, the ACBt-PAA/CMCs double network structured hydrogels exhibited excellent self-healing (the tensile strength recovered to 74.3 % after 1 h) and adjustable mechanical properties, in which the fracture stress and strain can be easily adjusted in the range of 0.039 to 0.93 MPa and 564 to 2900 %, respectively. In addition, the ACBt-PAA/CMCs hydrogels exhibited the remarkable antibacterial activities against Escherichia coli (bacterial inhibition efficiency of ~99.99 %) and Staphylococcus aureus (bacterial inhibition efficiency of ~99.98 %). Furthermore, the ACBt-PAA/CMCs hydrogel based wearable skin exhibited an excellent real-time sensing performance for monitoring various motions, signifying outstanding sensing and self-adhesion properties. Considering the unique features such as self-healing, excellent adhesion, highly active strain sensing, and antibacterial activities making the ACBt-PAA/CMCs hydrogel is an excellent multifunctional conductive hydrogel. Hence, we believe that this proposed design method for the fabrication of smart and multifunctional conductive hydrogels, and this ACBt-PAA/CMCs hydrogel could be a promising candidate for flexible wearable materials, health monitoring, and beyond.

Relationship Between COVID-19 Infection and Risk Perception, Knowledge, Attitude, and Four Nonpharmaceutical Interventions During the Late Period of the COVID-19 Epidemic in China: Online Cross-Sectional Survey of 8158 Adults.

BACKGROUND: So far, there have been no published population studies on the relationship between a COVID-19 infection and public risk perception, information source, knowledge, attitude, and behaviors during the COVID-19 outbreak in China. OBJECTIVE: This study aims to understand the relationships between COVID-19 infection; four personal nonpharmaceutical interventions (NPIs; handwashing, proper coughing habits, social distancing, and mask wearing); and public risk perception, knowledge, attitude, and other social demographic variables. METHODS: An online survey of 8158 Chinese adults between February 22 and March 5, 2020, was conducted. Bivariate associations between categorical variables were examined using Fisher exact test. We also explored the determinants of four NPIs as well as their association with COVID-19 infection using logistic regression. RESULTS: Of 8158 adults included, 57 (0.73%) were infected with COVID-19. The overwhelming majority of respondents showed a positive attitude (n=8094, 99.2%), positive risk perception (n=8146, 99.9%), and high knowledge levels that were among the strongest predictors of the four adopted NPIs (handwashing: n=7895, 96.8%; proper coughing: 5997/6444, 93.1%; social distancing: n=7104/8158, 87.1%; and mask wearing: 5011/5120, 97.9%). There was an increased risk of COVID-19 infection for those who did not wash their hands (2.28% vs 0.65%; risk ratio [RR] 3.53, 95% CI 1.53-8.15; P=.009), did not practice proper coughing (1.79% vs 0.73%; RR 2.44, 95% CI 1.15-5.15; P=.03), did not practice social distancing (1.52% vs 0.58%; RR 2.63, 95% CI 1.48-4.67; P=.002), and did not wear a mask (7.41% vs 0.6%; RR 12.38, 95% CI 5.81-26.36; P<.001). For those who did practice all other three NPIs, wearing a mask was associated with a significantly reduced risk of infection compared to those who did not wear a mask (0.6% vs 16.7%; P=.04). Similarly, for those who did not practice all or part of the other three NPIs, wearing a mask was also associated with a significantly reduced risk of infection. In a penalized logistic regression model including all four NPIs, wearing a mask was the only significant predictor of COVID-19 infection among the four NPIs (odds ratio 7.20, 95% CI 2.24-23.11; P<.001). CONCLUSIONS: We found high levels of risk perception, positive attitude, desirable knowledge, as well as a high level of adopting the four NPIs. The relevant knowledge, risk perception, and attitude were strong predictors of adapting the four NPIs. Mask wearing, among the four personal NPIs, was the most effective protective measure against COVID-19 infection, with added preventive effect among those who practiced all or part of the other three NPIs.

Monolithic integrated cyclic 64-channel AWG with MZI filters and arrayed vertical reflecting mirrors for WDM-PON application.

The paper introduces a silica-on-silicon monolithic integrated cyclic arrayed waveguide grating (AWG) with Mach-Zehnder interference (MZI) filters and arrayed vertical reflecting mirrors in silicon to realize effective and stable optical transmission between waveguides and photodiodes. The cyclic AWG acts as both multiplexer over the L-band for upstream traffic and demultiplexer over the C-band for downstream traffic. The integrated chip, including AWG, MZI filters, and arrayed reflecting mirrors, has been made successfully with a 6.0 dB insertion loss, which is less than the discrete devices. At the same time, the arrayed reflecting mirrors are more stable than separate reflectors.

Integrated athermal arrayed-waveguide grating multiplexer and demultiplexer with all-metal compensating rod for broadband temperature application.

In this paper, a unique device that can act as both multiplexer and demultiplexer is proposed with two all-metal compensating rods that makes the compensated chip almost the same spectrum profile as the original one. In this way a flat-top athermal arrayed-waveguide grating module of 100-GHz×40-ch is successfully fabricated. A small center wavelength shift of ±25 pm is achieved for the ultra-wide temperature range from -40°C to 85°C with the low insertion loss change of less than ±0.14 dB.

Molten salt synthesis and luminescent properties of YVO4:Ln (Ln = Eu3+, Dy3+) nanophosphors.

Eu3+ and Dy(3+)-doped YVO4 nanocrystallites were successfully prepared at 400 degrees C in equal moles of NaNO3 and KNO3 molten salts. X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, transmission electronic microscopy (TEM), photoluminescence (PL) spectrum and lifetime were used to characterize the nanocrystallites. XRD results demonstrate that NaOH concentration and annealing temperature play important roles in phase purity and crystallinity of the nanocrystallites, the optimum NaOH concentration and annealing temperature being 6:40 and 400 degrees C respectively. TEM micrographs show the nanocrystallites are well crystallized with a cubic morphology in an average grain size of about 18 nm. Upon excitation of the vanadate group at 314 nm, YVO4:Eu3+ and YVO4:Dy3+ nanocrystallites exhibit the characteristic emission of Eu3+ and Dy3+, which indicates that there is an energy transfer from the vanadate group to the rare earth ions. Moreover, the structure and luminescent properties of the nanocrystallites were compared with their bulk counterparts with same composition in detail.

Molten salt synthesis and luminescent properties of YVO4:Ln (Ln = Eu3+, Dy3+) nanophosphors.

Eu3+ and Dy(3+)-doped YVO4 nanocrystallites were successfully prepared at 400 degrees C in equal moles of NaNO3 and KNO3 molten salts. X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, transmission electronic microscopy (TEM), photoluminescence (PL) spectrum and lifetime were used to characterize the nanocrystallites. XRD results demonstrate that NaOH concentration and annealing temperature play important roles in phase purity and crystallinity of the nanocrystallites, the optimum NaOH concentration and annealing temperature being 6:40 and 400 degrees C respectively. TEM micrographs show the nanocrystallites are well crystallized with a cubic morphology in an average grain size of about 18 nm. Upon excitation of the vanadate group at 314 nm, YVO4:Eu3+ and YVO4:Dy3+ nanocrystallites exhibit the characteristic emission of Eu3+ and Dy3+, which indicates that there is an energy transfer from the vanadate group to the rare earth ions. Moreover, the structure and luminescent properties of the nanocrystallites were compared with their bulk counterparts with same composition in detail.

Preliminary proteomic analysis of human serum from patients with laryngeal carcinoma.

To better evaluate the serum protein alterations in patients with laryngeal carcinoma during surgical treatment process, a comparative proteomic analysis of human serum from patients with laryngeal carcinoma between pre- and post-operation group was performed using two-dimensional gel electrophoresis, in combination with matrix-assisted laser desorption ionization time-of-flight mass spectrometry and database searching. Statistical analysis indicated that 16 gel spots corresponding to 12 proteins altered their expression significantly between the two groups of patients with laryngeal carcinoma. Of these 12 proteins, 6 proteins were up-regulated in the pre-operation group. The subsequent Western blot confirmed the results of proteome analysis. Measurement of MDA and SOD levels in serum combining with bioinformatics analysis indicated the potential roles of the oxidant stress and immune response as target in monitoring and treating laryngeal carcinoma. The study provides new insight into the laryngeal carcinoma development and treatment, and the identified proteins are warranted to be further studied.