Effect of Preliminary Torsional Strain on Low-Cycle Fatigue of Q345B Structural Steel

Effect of preliminary torsional strain on low-cycle fatigue of Q345B steel was studied. The specimens were first 0, 180, and 360° twisted, then the low-cycle fatigue of Q345B steel was evaluated in the strain range of 0.3–0.8% by the method of axisymmetrical strain. The cycling response, cyclic stress–strain relationship, strain–life relationship, fatigue life prediction model, and seismic stability at different torsion angles were obtained and analyzed. The strain–life curve is shown to slope down as a power function. The fatigue life comes down with preliminary torsional strain at a constant level. The cycling response varied from cyclic hardening to cyclic softening in preliminary torsion, and the cyclic hardening rate increased linearly with the strain amplitude. The parameters of the Coffin–Manson relation are corroborated with experimental data. After heat treatment, the seismic stability of the material is improved, with torsional strain greatly reducing this characteristic. Electron microscope examination of fatigue fracture revealed a fatigue crack initiating on the surface of the specimen. The propagating crack deviated from its direction, and plasticity of the material dropped as a result of preliminary torsional strain.Изучено влияние деформации предварительного кручения на малоцикловую усталость стали Q345B. Вначале образцы скручивали на 0, 180 и 360°, затем методом осесимметричной деформации определяли малоцикловую усталость стали Q345B в диапазоне деформаций 0.3 0.8%. Получены и проанализированы характеристика циклических изменений, зависимость циклического изменения напряжения от деформации, зависимость деформация долговечность, модель прогнозирования усталостной долговечности и сейсмостойкость при различных углах кручения. Показано, что кривая деформация долговечность идет вниз и описывается степенной функцией. Усталостная долговечность снижается с увеличением деформации предварительного кручения при постоянном уровне последней. Характеристика циклических изменений варьировала от циклического упрочнения до циклического разупрочнения при кручении, скорость циклического упрочнения возрастала линейно с повышением амплитуды деформации. Параметры зависимости Коффина Мэнсона подтверждаются экспериментальными данными. После термообработки сейсмостойкость материала улучшается, при этом деформация предварительного кручения существенно снижает ее. Электронно-микроскопическое исследование усталостного разрушения выявило зарождение усталостной трещины на поверхности образца. Растущая трещина отклонялась от своего направления, пластичность материала снижалась в результате деформации предварительного кручения.Вивчено вплив деформації попереднього кручення на малоціклову втому стали Q345B. Спочатку зразки скручували на 0, 180 і 360 °, потім методом вісесиметричної деформації визначали малоціклову втому стали Q345B в діапазоні деформацій 0.3-0.8%. Отримано і проаналізовано характеристику циклічних змін, залежність циклічної зміни напржень від деформації, залежність деформація-довговічність, модель прогнозування втомної довговічності і сейсмостійкості при різних кутах кручення. Показано, що крива деформація - довговічність йде вниз і описується ступеневою функцією. Втомна довговічність знижується зі збільшенням деформації попереднього кручення при постійному рівні останньої. Характеристика циклічних змін варіювала від циклічного зміцнення до циклічного знеміцнення при крученні, швидкість циклічного зміцнення зростала лінійно з підвищенням амплітуди деформації. Параметри залежності Коффина-Менсона підтверджуються експериментальними даними. Після термообробки сейсмостійкість матеріалу поліпшується, при цьому деформація попереднього кручення істотно знижує її. Електронно-мікроскопічне дослідження втомного руйнування виявило зародження втомної тріщини на поверхні зразка. Зростаюча тріщина відхилялася від свого напрямку, пластичність матеріалу знижувалася в результаті деформації попереднього кручення

Changing trends in glaucoma surgery within Australia

Background: Limited data are available on glaucoma surgical trends in Australia. Methods: Nationwide study of glaucoma surgery in Australia over 17-year period from 2001 to 2018. The Australian Institute of Health, Welfare and Ageing hospitalisation database was used to review age- and gender-specific trends in glaucoma surgeries from 2001 to 2018 in Australian public and private hospitals. Results: Although there was an increase in the absolute number of trabeculectomy procedures from 2926 to 3244 over the 17-year study period, this represented a decline in the age-standardised and gender-standardised number of trabeculectomy procedures from 15.1 to 13.2 procedures per 100 000 persons. However, during this same period, there was a dramatic increase in the number of glaucoma drainage devices (GDD) from 119 to 3262 procedures, representing an age-standardised and gender-standardised increase from 0.6 to 13.3 procedures per 100 000 persons. Negative binomial regression analysis revealed a decrease in trabeculectomy procedures of 1.1% per year, while there was increase in GDD insertions of 16.3% per year (p60 years, compared with stable or increasing rates in younger age groups. GDD insertion rates demonstrated a progressively greater increase in older compared with younger age groups. Conclusion: Our findings demonstrate changing trends in the surgical management of advanced glaucoma in Australia, likely reflecting updated evidence regarding the role of GDD surgeries.Michelle T Sun, Reema Madike, Sonia Huang, Cassie Cameron, Dinesh Selva, Robert J Casson, Christopher X Won

Laser frequency stabilization using folded cavity and mirror reflectivity tuning

International audienceA new method of laser frequency stabilization using polarization property of an optical cavity is proposed. In a standard Fabry–Perot cavity, the coating layers thickness of cavity mirrors is calculated to obtain the same phase shift for sand p-wave but a slight detuning from the nominal thickness can produce sand p-wave phase detuning. As a result, each wave accumulates a different round-trip phase shift and resonates at a different frequency. Using this polarization property, an error signal is generated by a simple setup consisting of a quarter wave-plate rotated at 45°, a polarizing beam splitter and two photodiodes. This method exhibits similar error signal as the Pound–Drever–Hall technique but without need for any frequency modulation. Lock theory and experimental results are presented in this paper.

The flavor-changing bottom-strange quark production in the littlest Higgs model with T parity at the ILC

In the littlest Higgs model with T-parity (LHT) the mirror quarks induce the special flavor structures and some new flavor-changing (FC) couplings which could greatly enhance the production rates of the FC processes. We in this paper study some bottom and anti-strange production processes in the LHT model at the International Linear Collider (ILC), i.e., $e^+e^-\rightarrow b\bar{s}$ and $\gamma\gamma\rightarrow b\bar{s}$. The results show that the production rates of these processes are sizeable for the favorable values of the parameters. Therefore, it is quite possible to test the LHT model or make some constrains on the relevant parameters of the LHT through the detection of these processes at the ILC.Comment: 12 pages, 8 figure

Measurements of the observed cross sections for e+e−→e^+e^-\to exclusive light hadrons containing π0π0\pi^0\pi^0 at s=3.773\sqrt s= 3.773, 3.650 and 3.6648 GeV

By analyzing the data sets of 17.3, 6.5 and 1.0 pb$^{-1}$ taken, respectively, at $\sqrt s= 3.773$, 3.650 and 3.6648 GeV with the BES-II detector at the BEPC collider, we measure the observed cross sections for $e^+e^-\to \pi^+\pi^-\pi^0\pi^0$, $K^+K^-\pi^0\pi^0$, $2(\pi^+\pi^-\pi^0)$, $K^+K^-\pi^+\pi^-\pi^0\pi^0$ and $3(\pi^+\pi^-)\pi^0\pi^0$ at the three energy points. Based on these cross sections we set the upper limits on the observed cross sections and the branching fractions for $\psi(3770)$ decay into these final states at 90% C.L..Comment: 7 pages, 2 figure

Partial wave analysis of J/\psi \to \gamma \phi \phi

Using $5.8 \times 10^7 J/\psi$ events collected in the BESII detector, the radiative decay $J/\psi \to \gamma \phi \phi \to \gamma K^+ K^- K^0_S K^0_L$ is studied. The $\phi\phi$ invariant mass distribution exhibits a near-threshold enhancement that peaks around 2.24 GeV/$c^{2}$. A partial wave analysis shows that the structure is dominated by a $0^{-+}$ state ($\eta(2225)$) with a mass of $2.24^{+0.03}_{-0.02}{}^{+0.03}_{-0.02}$ GeV/$c^{2}$ and a width of $0.19 \pm 0.03^{+0.06}_{-0.04}$ GeV/$c^{2}$. The product branching fraction is: $Br(J/\psi \to \gamma \eta(2225))\cdot Br(\eta(2225)\to \phi\phi) = (4.4 \pm 0.4 \pm 0.8)\times 10^{-4}$.Comment: 11 pages, 4 figures. corrected proof for journa

Detection of polymorphisms and protein domain architectures in rabbit toll-like receptor 2

[EN] Toll-like receptors (TLRs) recognise pathogen-associated molecular patterns (PAMPs) derived from pathogens and participate in activation of the immune responses. The TLR2 gene can recognise PAMPs specific to bacterial diseases such as pneumonia. In the present study, we sequenced the coding regions of the TLR2 gene in 18 rabbits from 5 breeds, including New Zealand White, Californian, Flemish Giant, Chinchilla and Fu Jian Yellow. In total, we discovered 11 single nucleotide polymorphisms (SNPs), including 4 non-synonymous SNPs located within the predicted TLR domains. Two non-synonymous SNPs (G205A and G265C) were located in the LRR (leucine-rich repeat) domains of the predicted protein, while another non-synonymous SNP (C943T) was situated in the regions involved in binding to ligands. In addition, one synonymous SNP (C1174T) was distributed in the nucleus regions of heterodimers formed. Then, we revealed five conservative regions in the LRR patterning by prediction and comparison of TLR2 protein domain architectures for multiple species. The SNPs in the TLR2 gene may increase the probability of adaptation to variability of PAMPs due to the rapid evolution of pathogens and the possibility of survival in rabbit populations. The SNPs reported here will be useful to investigate the association between the TLR2 gene and disease resistance in future studies.This work was supported by funding from Sichuan Animal Science Academy and Applied Basic Research Programmes of the Science and Technology Foundation of Sichuan Province.Zhang, X.; Lei, M.; Xie, L.; Zhang, C.; Zheng, J.; Yang, C.; Deng, XD.... (2014). Detection of polymorphisms and protein domain architectures in rabbit toll-like receptor 2. World Rabbit Science. 22(1):83-90. doi:10.4995/wrs.2014.1457SWORD839022