Vibration Analysis of Porous Cu-Si Microcantilever Beams in Fluids Based on Modified Couple Stress Theory.

The vibrations in functionally graded porous Cu-Si microcantilever beams are investigated based on physical neutral plane theory, modified coupled stress theory, and scale distribution theory (MCST&SDT). Porous microcantilever beams define four pore distributions. Considering the physical neutral plane theory, the material properties of the beams are computed through four different power-law distributions. The material properties of microcantilever beams are corrected by scale effects based on modified coupled stress theory. Considering the fluid driving force, the amplitude-frequency response spectra and resonant frequencies of the porous microcantilever beam in three different fluids are obtained based on the Euler-Bernoulli beam theory. The quality factors of porous microcantilever beams in three different fluids are derived by estimating the equation. The computational analysis shows that the presence of pores in microcantilever beams leads to a decrease in Young's modulus. Different pore distributions affect the material properties to different degrees. The gain effect of the scale effect is weakened, but the one-dimensional temperature field and amplitude-frequency response spectra show an increasing trend. The quality factor is decreased by porosity, and the degree of influence of porosity increases as the beam thickness increases. The gradient factor n has a greater effect on the resonant frequency. The effect of porosity on the resonant frequency is negatively correlated when the gradient factor is small (n<1) but positively correlated when the gradient factor is large (n>1).

Size-Dependent Buckling and Post-Buckling Analysis of the Functionally Graded Thin Plate Al-Cu Material Based on a Modified Couple Stress Theory.

Size-dependent functionally graded material thin plate buckling and post-buckling problems are considered using the framework of the MCST (Modified Couple Stress Theory). Based on modified couple stress theory and power law, the post-buckling deflection and critical buckling load of simply supported functionally graded material thin plate are derived using Hamilton's minimum potential energy principle. The analysis compares the simulation results of linear buckling and nonlinear buckling. Innovatively, a power-law distribution with scale effects is considered. The influences of scale effect parameters l and power-law index parameters k on buckling displacement, load, and strain energy of plates have been investigated. In this article, it is found that the critical buckling displacement, critical buckling load, and buckling strain energy increase with increases in the power-law index parameters k. The membrane energy decreases as the power-law index parameter increases. If the upper and lower layers are swapped, the opposite result is obtained. In comparison, the scale effect parameter is more influential than the power-law exponent. The critical buckling displacement in the x-direction is not affected by scale effects. The critical buckling load, the membrane energy, and buckling strain energy increase as the scale effect parameter increases. Scale effects increase material stiffness compared with traditional theory, and the power-law index parameters affect FGM properties such as elastic modulus, Poisson's ratio, density, etc. Both scale effects parameters and power-law index parameters have important effects on the mechanical behavior of materials.

Efficiency comparison with fovea-sparing internal limiting membrane peeling and complete internal limiting membrane peeling for treating myopic traction maculopathy.

PURPOSE: To explore whether the efficacy of fovea-sparing internal limiting membrane peeling (FS-ILMP) is better than that of complete internal limiting membrane peeling (ILMP). METHODS: This retrospective clinical study included 34 cases (34 eyes) with myopic traction maculopathy collected from June 2017 to February 2019. Twenty-three-gauge (23-G) pars plana vitrectomy (23G PPV) was performed on all patients. In the FS-ILMP group, 18 eyes retained the internal limiting membrane (ILM) of about 1 to 1.5 papillary diameter centered on fovea centralis, while in the standard ILMP group, the ILM was completely removed from 16 eyes. The best corrected visual acuity (BCVA), central foveal thickness (CFT), and other indexes were collected before and 6 months after surgery. RESULTS: There was no significant difference in baseline clinical characteristics between the two groups. CFT and BCVA were significantly improved in both FS-ILMP and standard ILMP group, but the postoperative BCVA of the FS-ILMP group was significantly better than that of the standard ILMP group (P < 0.001). Two cases of subretinal effusion in macula were recorded in the FS-ILMP group, and three eyes in the standard ILMP group developed macular holes after surgery. Although both treatments relieved the mechanical traction of macular fovea, the patients in the FS-ILMP group showed better clinical outcomes in various aspects. CONCLUSION: These results improved our understanding of the clinical application of vitrectomy combined with preservation of ILM upon the fovea centralis, which might lay a foundation for in-depth study on the treatment of myopic traction maculopathy.

ONE Health Approach to Address Zoonotic Brucellosis: A Spatiotemporal Associations Study Between Animals and Humans.

Background: Brucellosis is one of the most significant zoonosis over the world, threatening both veterinary and human public health. However, few studies were focused on nationwide animal brucellosis and made association with human brucellosis. Methodology and Principal Findings: We conducted a bilingual literature search on Brucella or brucellosis in China on the two largest databases (China National Knowledge Infrastructure and PubMed) and conducted a systematic review. A total of 1,383 Chinese and 81 English publications, published between 1958 and 2018 were identified. From them, 357 publications presenting 692 datasets were subjected to the meta-analysis. The overall prevalence rate is 1.70% (95% CI: 1.66-1.74), with a declining (until the late 1990s) and rising trend (starting the early 2000s). Interestingly, the animal with highest prevalence rate is canine (8.35%, 95% CI: 7.21-9.50), and lowest in cattle (1.22%, 95% CI: 1.17-1.28). The prevalence of Brucella in animals was unequally distributed among the 24 examined regions in China. Conclusions: Brucellosis is a reemerging disease for both humans and animals in China. The observed data suggests that dogs and yaks are the leading reservoirs for Brucella, and the provinces with highest prevalence rates in animals are Hubei, Sichuan, Inner Mongolia, Fujian, and Guizhou. Accordingly targeted intervention policy should be implemented to break the Brucella transmission chain between animals and humans in China.

Surgical treatment for type II macular hole retinal detachment in pathologic myopia.

To observe the effectiveness and complications of inverted internal limiting membrane insertion through 25-G minimally invasive vitrectomy assisted with autologous blood adhesion fixation and combined with gas tamponade type-II macular hole retinal detachment in pathologic myopia.This was a retrospective study. The best-corrected visual acuity, intraocular pressure, macular hole closure, retinal reattachment, and systemic and ocular adverse events were observed.Twenty-three eyes were operated. Best-corrected visual acuity before surgery and at 3 and 6 months were 2.25 ±â€Š0.47, 1.85 ±â€Š0.32, and 1.32 ±â€Š0.36 LogMAR (P < .001). On days 2 to 5, all the retinas reattached, and the macular holes closed. On days 5 to 9, 5 eyes showed increased intraocular pressure. At 2 and 4 months, 2 eyes showed retinal detachment recurrence. No serious systemic or ocular adverse events were observed.This surgical technique showed clinical benefits and no significant complications. Clinical trials are necessary to confirm efficacy and safety.