The Finite Spectrum of Fourth-Order Boundary Value Problems with Transmission Conditions

A class of fourth-order boundary value problems with transmission conditions are investigated. By constructing we prove that these class of fourth order problems consist of finite number of eigenvalues. Further, we show that the number of eigenvalues depend on the order of the equation, partition of the domain interval, and the boundary conditions (including the transmission conditions) given

Thermodynamic Cycle Analysis and Experimental Investigate on a Two-stage Vapor Injection Low Temperature Air Source Heat Pump with a Variable Displacement Ratio Rotary Compressor

Two-stage vapor injection compression cycle with flash tank was thermodynamically analyzed, the results showed that there existed the optimum theoretical displacement ratio of high stage to low stage corresponding to the maximum coefficient of performance(COP), the optimum displacement ratio and the volumetric heating capacity decreased with evaporation temperature decreasing. An optimum theoretical displacement ratio correlation for R290, R32 and R410A was given. A new type two-stage vapor injection low temperature air source heat pump (ASHP) was designed, which had a variable speed triple-cylinder rotary compressor with two cylinders in low stage and one cylinder in high stage. The experimental results of the new type ASHP showed that the heating capacity under 20℃/-20℃(inside room /outside room) could reach the rated heating capacity under 20℃/7℃, improving 96% compared to conventional one-stage ASHP, the heating capacity under 20℃/-30℃ could reach 80% of the rated one. COP of the new type ASHP could improve 5%~10% when the heating capacity was comparable to the conventional ASHP, and the heating capacity of the new type ASHP could improve 30%~50% when COP was comparable to the conventional ASHP

catena-Poly[[triaqua­(pyridine-κN)nickel(II)]-μ-sulfato-κ2 O:O′]

The title compound, [Ni(SO4)(C5H5N)(H2O)3]n, was synthesized by the hydro­thermal reaction of NiSO4·6H2O, pyridine and water. The central NiII atom is coordinated in a distorted octa­hedral environment by a pyridine N atom, three aqua O atoms and two O atoms of bridging sulfate anions, yielding a zigzag chain. A three-dimensional network is generated via complex hydrogen bonds involving the sulfate and aqua ligands and a pyridine C—H group

Enhancement of polar phases in PVDF by forming PVDF/SiC nanowire composite

Different contents of silicon carbide (SiC) nanowires were mixed with Poly(vinylidene fluoride) (PVDF) to facilitate the polar phase crystallization. It was shown that the annealing temperature and SiC content affected on the phase and crystalline structures of PVDF/SiC samples. Furthermore, the addition of SiC nanowire enhanced the transformation of non-polar α phase to polar phases and increased the relative fraction of β phase in PVDF. Due to the nucleating agent mechanism of SiC nanowires, the ion-dipole interaction between the negatively charged surface of SiC nanowires and the positive CH2 groups in PVDF facilitated the formation of polar phases in PVDF

Gendered factors associated with preventive behaviors and mental health among Chinese adults during the COVID-19 pandemic home quarantine

The outbreak of the coronavirus disease in 2019 (COVID-19) has greatly impacted the life and mental health of many people globally. The objective of this study was to investigate the factors associated with preventive behaviors and mental health among Chinese adults during their home quarantine in the COVID-19 period. An online questionnaire survey was administered in March 2020. The study participants were adults aged between 18 and 70 years old from 31 provinces in China. Of the 3878 participants, 1314 reported moderate levels of anxiety, and the remaining participants reported moderate to severe levels of anxiety. Findings revealed that females aged between 18 and 30 years old who had higher educational qualifications, greater levels of preventive knowledge, trust in the government, and resided in urban and medium-risk areas (R2 = 0.100, F = 27.97, p < 0.001) were more likely to exhibit preventive behaviors. In contrast, a higher negative emotional response was generally seen in males who had low levels of preventive knowledge and behaviors, higher risk perception of infection, lower trust in the government, and unhealthy lifestyles (R2 = 0.127, F = 32.33, p < 0.001). In addition, the high-risk perception of infection was positively associated with high odds of anxiety (AOR = 1.17, 95% CI: 1.10–1.24), whereas a greater level of preventive knowledge (AOR = 0.36, 95% CI: 0.19–0.70) and behaviors (AOR = 0.69, 95% CI: 0.57–0.84), higher trust in the government’s COVID-19 pandemic mitigation measures (AOR = 0.77, 95% CI: 0.71–0.83), and a healthier lifestyle (AOR = 0.89, 95% CI: 0.79–0.99) were negatively associated with high odds of anxiety. Results showed that a lower level of anxiety and negative emotional response were associated with better preventive behaviors against COVID-19, which were influenced by preventive knowledge, risk perception, trust in the government’s COVID-19 pandemic mitigation measures, and healthy lifestyle. Findings in this study could help formulate health interventions for vulnerable groups related to gendered vulnerabilities in the COVID-19 environment to improve their mental health and preventive behaviors, especially during the period of a pandemic

The Flare and Warp of the Young Stellar Disk traced with LAMOST DR5 OB-type stars

We present analysis of the spatial density structure for the outer disk from 8$-$14 \,kpc with the LAMOST DR5 13534 OB-type stars and observe similar flaring on north and south sides of the disk implying that the flaring structure is symmetrical about the Galactic plane, for which the scale height at different Galactocentric distance is from 0.14 to 0.5 \,kpc. By using the average slope to characterize the flaring strength we find that the thickness of the OB stellar disk is similar but flaring is slightly stronger compared to the thin disk as traced by red giant branch stars, possibly implying that secular evolution is not the main contributor to the flaring but perturbation scenarios such as interactions with passing dwarf galaxies should be more possible. When comparing the scale height of OB stellar disk of the north and south sides with the gas disk, the former one is slightly thicker than the later one by $\approx$ 33 and 9 \,pc, meaning that one could tentatively use young OB-type stars to trace the gas properties. Meanwhile, we unravel that the radial scale length of the young OB stellar disk is 1.17 $\pm$ 0.05 \,kpc, which is shorter than that of the gas disk, confirming that the gas disk is more extended than stellar disk. What is more, by considering the mid-plane displacements ($Z_{0}$) in our density model we find that almost all of $Z_{0}$ are within 100 \,pc with the increasing trend as Galactocentric distance increases.Comment: 14 pages and 8 figures, Accepted by APJ for publicatio

Experimental study of THGEM detector with mini-rim

The gas gain and energy resolution of single and double THGEM detectors (5{\times}5cm2 effective area) with mini-rims (rim is less than 10{\mu}m) were studied. The maximum gain can reach 5{\times}103 and 2{\times}105 for single and double THGEM respectively, while the energy resolution of 5.9 keV X-ray varied from 18% to 28% for both single and double THGEM detectors of different hole sizes and thicknesses.All the experiments were investigated in mixture of noble gases(argon,neon) and small content of other gases(iso-butane,methane) at atmospheric pressure.Comment: 4pages,6figures, it has been submitted to Chinese Physics