Deadzone compensation control based on detection of micro flow rate in pilot stage of proportional directional valve

The pilot operated proportional directional valves (POPDVs) with a flow rate ranging from 100 to 1000 L/min are widely used in electro-hydraulic systems (EHSs). The deadzone of the pilot stage valve and its control compensation could significantly affect the position control performance for the main stage valve that could directly affect dynamics of EHSs In this paper, it is concluded that micro flow rates exist at the intermediate position of the valve based on the analysis of the continuity equation of the flow in the control chamber of the pilot stage. The micro flow rate is helpful to eliminate the discontinuity and unsmooth domain in the previous inverse deadzone compensation function. An improved deadzone detection method is proposed to calibrate the pilot valve flow characteristics which include the micro flow rate. This new method avoids the threshold selection of the main valve spool displacement which affects the detected deadzone values. Its detection processes are realized based on the pilot flow rate characterized by the speed of the main valve spool and the pilot valve displacement characterized by the solenoid current. The deadzone compensation control strategy based on the improved deadzone detection method is also designed. The experimental results using the steady-state position tracking and sinusoidal position tracking methods are verified. It is concluded that the tracking accuracy of the main valve spool position is effectively improved with this control strategy

Photoacoustic imaging of living mouse brain vasculature using hollow gold nanospheres

Photoacoustic tomography (PAT) also referred to as optoacoustic tomography (OAT) is a hybrid imaging modality that employs nonionizing optical radiation and ultrasonic detection. Here, we describe the application of a new class of optical contrast agents based on mesoscopic hollow gold nanospheres (HAuNS) to PAT. HAuNS are ∼40 nm in diameter with a hollow interior and consist of a thin gold wall. They display strong resonance absorption tuned to the near-infrared (NIR) range, with an absorption peak at 800 nm, whose photoacoustic efficiency is significantly greater than that of blood. Following surface conjugation with thiolated poly(ethylene glycol), the pegylated HAuNS (PEG-HAuNS) had distribution and elimination half-lives of 1.38 ± 0.38 and 71.82 ± 30.46 h, respectively. Compared with PAT images based on the intrinsic optical contrast in nude mice, the PAT images acquired within 2 h after intravenous administration of PEG-HAuNS showed the brain vasculature with greater clarity and detail. The image depicted brain blood vessels as small as ∼100 μm in diameter using PEG-HAuNS as contrast agents. Preliminary results showed no acute toxicity to the liver, spleen, or kidneys in mice following a single imaging dose of PEG-HAuNS. Our results indicate that PEG-HAuNS are promising contrast agents for PAT, with high spatial resolution and enhanced sensitivity

Physical Exercise Regulates p53 Activity Targeting SCO2 and Increases Mitochondrial COX Biogenesis in Cardiac Muscle with Age

The purpose of this study was to outline the timelines of mitochondrial function, oxidative stress and cytochrome c oxidase complex (COX) biogenesis in cardiac muscle with age, and to evaluate whether and how these age-related changes were attenuated by exercise. ICR/CD-1 mice were treated with pifithrin-μ (PFTμ), sacrificed and studied at different ages; ICR/CD-1 mice at younger or older ages were randomized to endurance treadmill running and sedentary conditions. The results showed that mRNA expression of p53 and its protein levels in mitochondria increased with age in cardiac muscle, accompanied by increased mitochondrial oxidative stress, reduced expression of COX subunits and assembly proteins, and decreased expression of most markers in mitochondrial biogenesis. Most of these age-related changes including p53 activity targeting cytochrome oxidase deficient homolog 2 (SCO2), p53 translocation to mitochondria and COX biogenesis were attenuated by exercise in older mice. PFTμ, an inhibitor blocking p53 translocation to mitochondria, increased COX biogenesis in older mice, but not in young mice. Our data suggest that physical exercise attenuates age-related changes in mitochondrial COX biogenesis and p53 activity targeting SCO2 and mitochondria, and thereby induces antisenescent and protective effects in cardiac muscle

Plasma optical modulators for intense lasers

Optical modulators can be made nowadays with high modulation speed, broad bandwidth, while being compact, owing to the recent advance in material science and microfabrication technology. However, these optical modulators usually work for low intensity light beams. Here, we present an ultrafast, plasma-based optical modulator, which can directly modulate high power lasers with intensity up to 10 16 W c

Protective effect of ginsenoside Rb1 against intestinal ischemia-reperfusion induced acute renal injury in mice

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ESC-Derived Basal Forebrain Cholinergic Neurons Ameliorate the Cognitive Symptoms Associated with Alzheimer’s Disease in Mouse Models

SummaryDegeneration of basal forebrain cholinergic neurons (BFCNs) is associated with cognitive impairments of Alzheimer’s disease (AD), implying that BFCNs hold potentials in exploring stem cell-based replacement therapy for AD. However, studies on derivation of BFCNs from embryonic stem cells (ESCs) are limited, and the application of ESC-derived BFCNs remains to be determined. Here, we report on differentiation approaches for directing both mouse and human ESCs into mature BFCNs. These ESC-derived BFCNs exhibit features similar to those of their in vivo counterparts and acquire appropriate functional properties. After transplantation into the basal forebrain of AD model mice, ESC-derived BFCN progenitors predominantly differentiate into mature cholinergic neurons that functionally integrate into the endogenous basal forebrain cholinergic projection system. The AD mice grafted with mouse or human BFCNs exhibit improvements in learning and memory performances. Our findings suggest a promising perspective of ESC-derived BFCNs in the development of stem cell-based therapies for treatment of AD

Thyroid function, renal function, and depression: an association study

ObjectiveTo investigate the correlations between thyroid function, renal function, and depression.MethodsClinical data of 67 patients with Major depressive disorder (MDD) and 36 healthy control subjects between 2018 and 2021 were collected to compare thyroid and renal function. Thyroid and renal functions of depressed patients were then correlated with the Hamilton Depression Rating Scale (HAMD) and the Hamilton Anxiety Rating Scale (HAMA).Spearman correlation analysis was used to find the correlation between renal function, thyroid function, and depression. A logistic regression was performed to find significant predictors of depression.ResultsTriiodothyronine protamine (T3), thyroxine (T4), free triiodothyronine protamine (FT3), uric acid, sodium, and anion gap were lower in the MDD group than in the control group (p < 0.05). Correlation analysis of thyroid function, renal function, and factor terms of HAMD in the MDD group suggested that diurnal variation, hopelessness, and depression level were positively correlated with thyrotropin (TSH) (p < 0.05). Cognitive disturbance, retardation, and depression level were negatively correlated with creatinine (p < 0.05). Diurnal variation was negatively correlated with sodium ion (p < 0.01); hopelessness and depression level were positively correlated with chloride ion (p < 0.05); diurnal variation, retardation, and depression level were negatively correlated with anion gap (p < 0.05). Diurnal variation (p < 0.01) and retardation (p < 0.05) were negatively correlated with osmolality. Cognitive disturbance and depression level were positively correlated with estimated glomerular filtration rate (eGFR) (p < 0.05). In the MDD group, correlation analysis of thyroid function, renal function, and HAMA factor terms suggested that the total HAMA score and anxiety level were positively correlated with chloride ion (p < 0.05); psychic anxiety, total HAMA score, and anxiety level were negatively correlated with anion gap (p < 0.05). Furthermore, a low level of anion gap was an independent risk factor for depression and anxiety levels (p < 0.05).ConclusionLow thyroid function and reduced waste metabolized by the kidneys in patients with MDD suggest a low intake and low metabolism in depressed patients. In addition, subtle fluctuations in the anion gap in depressed patients were strongly correlated with the degree of depression and anxiety

Discovery of six high-redshift quasars with the Lijiang 2.4m telescope and the Multiple Mirror Telescope

Quasars with redshifts greater than 4 are rare, and can be used to probe the structure and evolution of the early universe. Here we report the discovery of six new quasars with $i$-band magnitudes brighter than 19.5 and redshifts between 2.4 and 4.6 from the YFOSC spectroscopy of the Lijiang 2.4m telescope in February, 2012. These quasars are in the list of $z>3.6$ quasar candidates selected by using our proposed $J-K/i-Y$ criterion and the photometric redshift estimations from the SDSS optical and UKIDSS near-IR photometric data. Nine candidates were observed by YFOSC, and five among six new quasars were identified as $z>3.6$ quasars. One of the other three objects was identified as a star and the other two were unidentified due to the lower signal-to-noise ratio of their spectra. This is the first time that $z>4$ quasars have been discovered using a telescope in China. Thanks to the Chinese Telescope Access Program (TAP), the redshift of 4.6 for one of these quasars was confirmed by the Multiple Mirror Telescope (MMT) Red Channel spectroscopy. The continuum and emission line properties of these six quasars, as well as their central black hole masses and Eddington ratios, were obtained.Comment: 7 pages, 2 figures, published in Research in Astronomy and Astrophysics (RAA) as a lette