Experimental and numerical investigation into effect of elevated temperature on fretting fatigue behavior

Fretting fatigue damage occurs in contacting parts when they are subjected to fluctuating loadings and sliding movements at the same time. This phenomenon may occur in many applications such as bearings/ shafts, bolted and riveted connections, steel cables, and steam and gas turbines. In this paper, the effect of elevated temperature on fretting fatigue life of Al7075-T6 is investigated using a new device for fretting fatigue tests with variable crank shaft mechanism. Also a finite element modeling method was used to estimate crack propagation lifetime in aluminum alloy, Al7075-T6 specimens at elevated temperature under fretting condition. In this method, shear and normal stresses that are caused by contact load are updated at each crack growth increment. Finally, a comparison between the experimental and numerical results is done in order to evaluate the FE simulation. Department of mechanical engineering, Islamic Azad University, Takestan Branch, Takestan, Iran The experimental results show that: (i) fretting fatigue life of the material increases with temperature up to 350°C by 180% for low stresses and decreases by 40% for high stresses, (ii) this fashion of variation of fretting fatigue life versus temperature is believed to be due to degradation of material properties which occurs by overaging and wear resistance increase due to oxidation of aluminum alloy. While overaging gives rise to degradation of mechanical strength of material and hence the reduction of its fretting fatigue life, surface oxidation of the specimens brings some improvement of fatigue behavior of the material. Metallurgical examination of the specimens reveals that temperature results in precipitation of impurities of al-7075-T6. The size of precipitated impurities and their distances gets bigger as temperature increases. This could be a reason for material degradation of specimens which are exposed to heating for longer time duration

Effect of hydro-alcoholic extract of Ziziphus jujuba on the peripheral blood cells in Balb/c mice

Introduction: In the Iranian traditional medicine, Ziziphus jujuba is recommended for treatment of anemia, but no investigation has addressed this issue. In the present study, the effect of hydro-alcoholic extract of this plant was evaluated on the peripheral blood cells in male Balb/c mice. Methods: Hydro-alcoholic extract was prepared from the fruits of the Ziziphus jujuba. Male mice were injected with normal saline or the extract (100, 200 or 400 mg/kg, i.p.) for a period of two weeks. Afterwards, the mice were anesthetized and blood samples were taken from their hearts and then the peripheral blood was evaluated by a Cell Counter apparatus. White blood cells differential analysis was manually performed under a microscope. Data was statistically analyzed using One-way ANOVA followed by Tukey post-hoc test. Results: Ziziphus jujuba extracts (100 and 400 mg/kg) caused a significant reduction in the percentages of monocytes and neutrophils, respectively (P0.05). Conclusion: Findings of this study show that Ziziphus jujuba extract increases the percentage of lymphocytes and also reduces the percentage of monocytes and neutrophils

Evaluating the Performance of Flow Cytometric Method in Identification of Platelet Resistance in Patients with Acute Myeloid Leukemia (AML)

BACKGROUND AND OBJECTIVE: Immune platelet resistance is a condition in which antibodies are produced against platelet antigens and cause damage to injected platelets by phagocytes and macrophages. The aim of this study is to evaluate the efficacy of flow cytometry in predicting the results of platelet injections and platelet resistance and selecting compatible platelet for patients. METHODS: This case-control study was performed on 15 patients with acute myeloid leukemia (AML) with two or multiple injections of platelets and 15 healthy subjects without a history of platelet injection. After marking the platelets with 5-Chloromethylfluorescein diacetate (CMFDA) and their adjacency to the serum of patients, the amount of phagocytosis of platelets by monocytes was assessed in the two groups. FINDINGS: The mean phagocytic power of platelets by monocyte was 18.27 ± 2.86% in the control group, 68.47 ± 10.40% in the group of patients with immune platelet resistance, and 36.73 ± 15.21 in the group of patients without immune platelet resistance (p = 0.001). In addition, there was a significant negative correlation between phagocytic power of platelets by monocyte and Corrected Count Increment (CCI) at 1 and 24 hours (p = - 0.001). CONCLUSION: Based on the results of this study and considering the high sensitivity of the flow cytometric method, the use of CMFDA is highly appropriate for evaluating platelet studies, and it can also be used for platelet crossmatch by flow cytometry

Throughfall Nutrients in a Degraded Indigenous Fagus Orientalis Forest and a Picea Abies Plantation in the of North of Iran

Aim of study: The objective of this study was to compare the quantity and quality of TF (throughfall) in an indigenous, but degraded, stand of Fagus orientalis and Picea abies plantation. Area of study: Forests of Kelar-Dasht region located in Mazandaran province, northern Iran. Material and Methods: TF measured by twenty collectors that were distributed randomly underneath each stand. For 21 storms sampled in 2012 (August-December) and 2013 (April-June), we analyzed pH, EC, Ca2+, Mg2+, K+, NO3-, and P of gross rainfall (GR) and TF. Main results: Cumulative interception (I) for F. orientalis and P. abies were 114.2 mm and 194.8 mm of the total GR, respectively. The amount of K+ (13.4 mg L-1) and Ca2+ (0.9 mg L-1) were higher (for both elements, p = 0.001) in the TF of P. abies compared to those of F. orientalis (6.8 and 0.5, mg L-1, respectively) and GR (3.2 and 0.37 mg L-1, respectively). Conversely, mean P concentration was doubled (p = 0.022) in the TF of F. orientalis (11.1 mg L-1) compared to GR (5.8 mg L-1). Research highlights: P. abies plantations may provide a solution for reforestation of degraded F. orientalis forests of northern Iran, yet how P. abies plantations differentially affect the quality and quantity of rainfall reaching subcanopy soils (TF) compared to F. orientalis is unknown. Understanding the connection between hydrological processes and nutrient cycling in forest ecosystems is crucial for choosing the appropriate species to rehabilitate the degraded indigenous forests with nonindigenous species

Kinase activity is not required for αCaMKII-dependent presynaptic plasticity at CA3-CA1 synapses

Using targeted mouse mutants and pharmacologic inhibition of αCaMKII, we demonstrate that the αCaMKII protein, but not its activation, autophosphorylation or its ability to phosphorylate synapsin I, is required for normal short-term presynaptic plasticity. Furthermore, αCaMKII regulates the number of docked vesicles independent of its ability to be activated. These results indicate that αCaMKII has a nonenzymatic role in short-term presynaptic plasticity at hippocampal CA3-CA1 synapses. © 2007 Nature Publishing Group

Randomised prospective trial to assess the clinical utility of multianalyte assay panel with complement activation products for the diagnosis of SLE.

Objective: We compared the physician-assessed diagnostic likelihood of SLE resulting from standard diagnosis laboratory testing (SDLT) to that resulting from multianalyte assay panel (MAP) with cell-bound complement activation products (MAP/CB-CAPs), which reports a two-tiered index test result having 80% sensitivity and 86% specificity for SLE. Methods: Patients (n=145) with a history of positive antinuclear antibody status were evaluated clinically by rheumatologists and randomised to SDLT arm (tests ordered at the discretion of the rheumatologists) or to MAP/CB-CAPs testing arm. The primary endpoint was based on the change in the physician likelihood of SLE on a five-point Likert scale collected before and after testing. Changes in pharmacological treatment based on laboratory results were assessed in both arms. Statistical analysis consisted of Wilcoxon and Fisher\u27s exact tests. Results: At enrolment, patients randomised to SDLT (n=73, age=48±2 years, 94% females) and MAP/CB-CAPs testing arms (n=72, 50±2 years, 93% females) presented with similar pretest likelihood of SLE (1.42±0.06 vs 1.46±0.06 points, respectively; p=0.68). Post-test likelihood of SLE resulting from randomisation in the MAP/CB-CAPs testing arm was significantly lower than that resulting from randomisation to SDLT arm on review of test results (-0.44±0.10 points vs -0.19±0.07 points) and at the 12-week follow-up visit (-0.61±0.10 points vs -0.31±0.10 points) (p Conclusion: Our data suggest that MAP/CB-CAPs testing has clinical utility in facilitating SLE diagnosis and treatment decisions

CFHTLenS and RCSLenS cross-correlation with Planck lensing detected in fourier and configuration space

We measure the cross-correlation signature between the Planck cosmic microwave background (CMB) lensing map and the weak lensing observations from both the Red-sequence Cluster Lensing Survey and the Canada–France–Hawaii Telescope Lensing Survey. In addition to a Fourier analysis, we include the first configuration-space detection, based on the estimators 〈κCMBκgal〉 and 〈κCMBγt〉. Combining 747.2 deg2 from both surveys, we find a detection significance that exceeds 4.2σ in both Fourier- and configuration-space analyses. Scaling the predictions by a free parameter A, we obtain APlanckCFHT=0.68±0.31 and APlanckRCS=1.31±0.33⁠. In preparation for the next generation of measurements similar to these, we quantify the impact of different analysis choices on these results. First, since none of these estimators probes the exact same dynamical range, we improve our detection by combining them. Secondly, we carry out a detailed investigation on the effect of apodization, zero-padding and mask multiplication, validated on a suite of high-resolution simulations, and find that the latter produces the largest systematic bias in the cosmological interpretation. Finally, we show that residual contamination from intrinsic alignment and the effect of photometric redshift error are both largely degenerate with the characteristic signal from massive neutrinos, however the signature of baryon feedback might be easier to distinguish. The three lensing data sets are publicly available

A new approach to cosmological perturbations in f(R) models

We propose an analytic procedure that allows to determine quantitatively the deviation in the behavior of cosmological perturbations between a given f(R) modified gravity model and a LCDM reference model. Our method allows to study structure formation in these models from the largest scales, of the order of the Hubble horizon, down to scales deeply inside the Hubble radius, without employing the so-called "quasi-static" approximation. Although we restrict our analysis here to linear perturbations, our technique is completely general and can be extended to any perturbative order.Comment: 21 pages, 2 figures; Revised version according to reviewer's suggestions; Typos corrected; Added Reference

Cosmological distance indicators

We review three distance measurement techniques beyond the local universe: (1) gravitational lens time delays, (2) baryon acoustic oscillation (BAO), and (3) HI intensity mapping. We describe the principles and theory behind each method, the ingredients needed for measuring such distances, the current observational results, and future prospects. Time delays from strongly lensed quasars currently provide constraints on $H_0$ with < 4% uncertainty, and with 1% within reach from ongoing surveys and efforts. Recent exciting discoveries of strongly lensed supernovae hold great promise for time-delay cosmography. BAO features have been detected in redshift surveys up to z <~ 0.8 with galaxies and z ~ 2 with Ly-$\alpha$ forest, providing precise distance measurements and $H_0$ with < 2% uncertainty in flat $\Lambda$CDM. Future BAO surveys will probe the distance scale with percent-level precision. HI intensity mapping has great potential to map BAO distances at z ~ 0.8 and beyond with precisions of a few percent. The next years ahead will be exciting as various cosmological probes reach 1% uncertainty in determining $H_0$, to assess the current tension in $H_0$ measurements that could indicate new physics.Comment: Review article accepted for publication in Space Science Reviews (Springer), 45 pages, 10 figures. Chapter of a special collection resulting from the May 2016 ISSI-BJ workshop on Astronomical Distance Determination in the Space Ag