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Previous walkability scoring systems are all based on road networks, even though roads are not designed for pedestrians. To calculate an accurate walking score, we need pedestrian network data. This is especially the case in cities such as Hong Kong, where pedestrians are separated from vehicles by footbridges, underpasses or surface sidewalks. In this paper, we investigate why and how a three-dimensional pedestrian network makes a difference in walkability scoring, using Hong Kong as a case city. We developed a walkability scoring system based on networks and amenities, using multiple open-source programming platforms and languages. Separately, we calculated walkability scores (on a scale of 0–100) using the three-dimensional pedestrian network and road network of the city, comparing the differences between the two. A GIS raster analysis was conducted to extract walkability scoring differences from the two walkability surfaces, followed by a univariate linear model to examine how the scores were underestimated if without using the three-dimensional pedestrian network. Results show that streets were considered twice as walkable if rated by pedestrian network rather than road network. Walkability scores were 92% higher on average. The fitted model shows that the mean score underestimations were significantly different for different three-dimensional network elements. Surface sidewalks had an average underestimation of 33.75 (p

Major depressive disorder (MDD) is a serious mental disorder that affects many people. The neurotransmitter deficiency hypothesis has been the crux of much research on the treatment of depression. Anhedonia, as a core symptom, was closely associated with altered levels of 5-hydroxytryptamine (5-HT), dopamine (DA), and diverse types of glutamate (Glu) receptors in the nucleus accumbens (NAc). However, there were no reports showing how Glu changed in the NAc, and there were other unreported molecules involved in modulating stress-induced anhedonia. Thus, we investigated changes in neurotransmitters and their related metabolites in GABAergic, serotonergic and catecholaminergic pathways in the NAc of a rat model of chronic unpredictable mild stress- (CUMS-) induced anhedonia-like behavior. Then, liquid chromatography-tandem mass spectrometry (LC-MS/MS) was employed to detect target neurotransmitters and related metabolites in the NAc. Finally, the Western blot was used to assess the expression of key enzymes and receptors. Here, we found that the 5-HT level in anhedonia-susceptible (Sus) rats was increased while the Glu level decreased. DA did not show a significant change among CUMS rats. Correspondingly, we detected a reduction in monoamine oxidase-A (MAOA) and Glu receptor 1 levels in anhedonia-Sus rats while Glu receptor 2 (GluR2) and NMDA2B levels were increased in anhedonia-resilient (Res) rats. We also found that the levels of glutamine (Gln), kynurenic acid (Kya), histamine (HA), L-phenylalanine (L-Phe), and tyramine (Tyra) were changed after CUMS. These alterations in neurotransmitters may serve as a new insight into understanding the development of anhedonia-like behavior in depression.

This paper examines how mass ridership data can help describe cities from the bikers' perspective. We explore the possibility of using the data to reveal general bikeability patterns in 202 major Chinese cities. This process is conducted by constructing a bikeability rating system, the Mobike Riding Index (MRI), to measure bikeability in terms of usage frequency and the built environment. We first investigated mass ridership data and relevant supporting data; we then established the MRI framework and calculated MRI scores accordingly. This study finds that people tend to ride shared bikes at speeds close to 10 km/h for an average distance of 2 km roughly three times a day. The MRI results show that at the street level, the weekday and weekend MRI distributions are analogous, with an average score of 49.8 (range 0–100). At the township level, high-scoring townships are those close to the city centre; at the city level, the MRI is unevenly distributed, with high-MRI cities along the southern coastline or in the middle inland area. These patterns have policy implications for urban planners and policy-makers. This is the first and largest-scale study to incorporate mobile bike-share data into bikeability measurements, thus laying the groundwork for further research.

Background The inflammation and oxidative stress (OS) have been considered crucial components of the pathogenesis of depression. Edaravone (EDA), a free radical scavenger, processes strong biological activities including antioxidant, anti-inflammatory and neuroprotective properties. However, its role and potential molecular mechanisms in depression remain unclear. The present study aimed to investigate the antidepressant activity of EDA and its underlying mechanisms. Methods A chronic social defeat stress (CSDS) depression model was performed to explore whether EDA could produce antidepressant effects. Behaviors tests were carried out to examine depressive, anxiety-like and cognitive behaviors including social interaction (SI) test, sucrose preference test (SPT), open field test (OFT), elevated plus maze (EPM), novel object recognition (NOR), tail suspension test (TST) and forced swim test (FST). Hippocampal and medial prefrontal cortex (mPFC) tissues were collected for Nissl staining, immunofluorescence, targeted energy metabolomics analysis, enzyme-linked immunosorbent assay (ELISA), measurement of MDA, SOD, GSH, GSH-PX, T-AOC and transmission electron microscopy (TEM). Western blotting (WB) and quantitative real-time polymerase chain reaction (qRT-PCR) detected the Sirt1/Nrf2/HO-1/Gpx4 signaling pathway. EX527, a Sirt1 inhibitor and ML385, a Nrf2 inhibitor were injected intraperitoneally 30 min before EDA injection daily. Knockdown experiments were performed to determine the effects of Gpx4 on CSDS mice with EDA treatment by an adeno-associated virus (AAV) vector containing miRNAi (Gpx4)–EGFP infusion. Results The administrated of EDA dramatically ameliorated CSDS-induced depressive and anxiety-like behaviors. In addition, EDA notably attenuated neuronal loss, microglial activation, astrocyte dysfunction, oxidative stress damage, energy metabolism and pro-inflammatory cytokines activation in the hippocampus (Hip) and mPFC of CSDS-induced mice. Further examination indicated that the application of EDA after the CSDS model significantly increased the protein expressions of Sirt1, Nrf2, HO-1 and Gpx4 in the Hip. EX527 abolished the antidepressant effect of EDA as well as the protein levels of Nrf2, HO-1 and Gpx4. Similarly, ML385 reversed the antidepressant and anxiolytic effects of EDA via decreased expressions of HO-1 and Gpx4. In addition, Gpx4 knockdown in CSDS mice abolished EDA-generated efficacy on depressive and anxiety-like behaviors. Conclusion These findings suggest that EDA possesses potent antidepressant and anxiolytic properties through Sirt1/Nrf2/HO-1/Gpx4 axis and Gpx4-mediated ferroptosis may play a key role in this effect.

Soil temperature plays an essential role in the permafrost thermal state and degradation process. Especially the soil temperatures at 10 cm and 50 cm depths in the active layer, which are much easier to be observed in situ, have great effects on the surface water cycles and vegetation, and could be used as the upper boundary for permafrost models to simulate the thermal state of the permafrost and active layer thicknesses. However, due to the limitations of the observation data, there are still large uncertainties in the soil temperature data, including at these two depths, in the permafrost region of Qinghai–Tibet Plateau (QTP). In this study, we evaluated and calibrated the applicability of four daily shallow soil temperature datasets (i.e., MERRA-2, GLDAS-Noah, ERA5-Land, and CFSR) by using the in situ soil temperature data from eight observation sites from 2004 to 2018 in the permafrost region along the Qinghai–Tibet Engineering Corridor. The results revealed that there were different uncertainties for all four sets of reanalysis data, which were the largest (Bias = −2.44 °C) in CFSR and smallest (Bias= −0.43 °C) in GLDAS-Noah at depths of 10 cm and 50 cm. Overall, the reanalysis datasets reflect the trends of soil temperature, and the applicability of reanalysis data at 50 cm depth is better than at 10 cm depth. Furthermore, the GLDAS-Noah soil temperatures were recalibrated based on our observations using multiple linear regression and random forest models. The accuracy of the corrected daily soil temperature was significantly improved, and the RMSE was reduced by 1.49 °C and 1.28 °C at the depth of 10 cm and 50 cm, respectively. The random forest model performed better in the calibration of soil temperature data from GLDAS-Noah. Finally, the warming rates of soil temperature were analyzed, which were 0.0994 °C/a and 0.1005 °C/a at 10 cm and 50 cm depth from 2004 to 2018, respectively.

Behavior models of electronic components are critical in many metrological and measurement areas, e.g., time-domain simulations for analog-integrated circuit design and predistortion of the amplifier to reduce the distortion. This paper describes the use of pulse-driven ac Josephson voltage standard (ACJVS) to synthesize quantum accurate waveforms with ultralow distortion and noise floor to model the amplifier nonlinearity, which is a promising way to increase the modeling accuracy. Four Volterra series models including the memory polynomial model and three submodels of the dynamic deviation reduction model are analyzed and compared in detail. Normalized mean square error is calculated to evaluate the modeling accuracy. The difference of the measured and predicted outputs of the amplifier are compared in both time and frequency domains. The result shows that high-performance models can be achieved, which demonstrates the feasibility of modeling nonlinear amplifier behavior with the ACJVS.

After continuous investigation on the electrical compensation method for the end effect error in the new vertical calculable cross-capacitor (VCCC), the latest optimal hollow active auxiliary electrode (OHAAE) has been developed and successfully substituted for the current geometrical nosepiece at one end of the movable guard electrode at the National Institute of Metrology, China (NIM). The critical electrical characteristics of the latest OHAAE are investigated by the model tests and eventually implemented with the least mechanical modifications to the new VCCC at NIM. The standard uncertainty of the reproduction of 1 pF capacitance unit from the new VCCC by adopting the latest OHAAE is decreased to $10.5 \times 10^{-9}$ in comparison with that of $20.0 \times 10^{-9}$ by the geometrical nosepiece.

This paper describes an absolute method for calibrating commercial 1000:1 dc current transducers (DCCTs). By adding two auxiliary windings to produce 10:1 and 100:1 ratios, we use a three-step build-up method to establish the 1000:1 current ratio standard. First, we determine the 10:1 ratios of 11 DCCTs through permutation; second, we set up a two-stage composite DCCT to produce a 100:1 ratio; after switching auxiliary windings in the two-stage setup, we then derive the 1000:1 current ratio. The experimental results show that the requirements for the current source and the current meter are not stringent; their Type-B contributions to the overall uncertainties are very small. Type-A uncertainties which include factors such as the experimental environment and possible drifts of the output offsets of the DCCTs are experimentally determined. Repeated tests show that the current ratio standard has an expanded uncertainty of $0.26 \times 10^{-6}$ for the 1000:1 ratio.

The freeze–thaw (F-T) cycle of the active layer (AL) causes the “frost heave and thaw settlement” deformation of the terrain surface. Accurately identifying its amplitude and time characteristics is important for climate, hydrology, and ecology research in permafrost regions. We used Sentinel-1 SAR data and small baseline subset-interferometric synthetic aperture radar (SBAS-InSAR) technology to obtain the characteristics of F-T cycles in the Zonag Lake-Yanhu Lake permafrost-affected endorheic basin on the Qinghai-Tibet Plateau from 2017 to 2019. The results show that the seasonal deformation amplitude (SDA) in the study area mainly ranges from 0 to 60 mm, with an average value of 19 mm. The date of maximum frost heave (MFH) occurred between November 27th and March 21st of the following year, averaged in date of the year (DOY) 37. The maximum thaw settlement (MTS) occurred between July 25th and September 21st, averaged in DOY 225. The thawing duration is the thawing process lasting about 193 days. The spatial distribution differences in SDA, the date of MFH, and the date of MTS are relatively significant, but there is no apparent spatial difference in thawing duration. Although the SDA in the study area is mainly affected by the thermal state of permafrost, it still has the most apparent relationship with vegetation cover, the soil water content in AL, and active layer thickness. SDA has an apparent negative and positive correlation with the date of MFH and the date of MTS. In addition, due to the influence of soil texture and seasonal rivers, the seasonal deformation characteristics of the alluvial-diluvial area are different from those of the surrounding areas. This study provides a method for analyzing the F-T cycle of the AL using multi-temporal InSAR technology.

In this study, we developed a series of second-order gradient overlap-coupling octagonal superconducting quantum interference device (SQUID) current sensors for transition edge sensor (TES) applications. According to the requirements of TESs, we designed various parameters of SQUID current sensors, including different Josephson junction (JJ) sizes, different hysteresis and screening parameters, input coils with different inductances. The superconducting loop, input coil, and feedback coil of the SQUID current sensors adopt a second-order gradient structure, which can effectively enhance their anti-interference electromagnetic capability. Further, all the coupling structures between the superconducting loop and input/feedback coil adopt overlap-coupling octagonal structures, which can effectively enhance the coefficient of coupling mutual inductance. A series of second-order gradient SQUID current sensors overlap-coupled with input coils of 1.5, 2.5, and 5.5 turns based on Nb/Al–AlO x /Nb JJs were successfully fabricated on 2 inch silicon wafers by optimising the fabrication processes. From the simulation results, a minimal magnetic coupling factor of 0.02 between the feedback coil and input coil is obtained in the overlapped structure of the SQUID current sensor with an input coil of 1.5 turns; thus the magnetic interference between the feedback coil and input coil in this design is negligible. According to the measurement results at liquid–helium temperatures, SQUID current sensors with second-order gradient overlap-coupling octagonal structures have an excellent capability to weaken environmental electromagnetic interference. The SQUID current sensor with an input coil of 5.5 turns has the smallest current sensitivity, 2.4 μA/Φ0 and lowest current noise, 1 pA (√Hz)−1 compared with those of other input coils of different turns. The SQUID current sensor with an input coil of 2.5 turns has the lowest flux noise, 0.3 μΦ0 (√Hz)−1, and the lowest coupled noise energy, 11 h, among all the three different input coils, which are balanced results between the input inductance and the device noise. SQUID current sensors with second-order gradient overlap-coupling octagonal structures show low flux noise, low current noise, and low coupled noise energy, which can be compared with the state-of-art SQUID current sensor worldwide, and can satisfy the requirements of TES applications.

Aquaculture ponds are of increasing worldwide concerns as critical sources of atmospheric methane (CH4) and nitrous oxide (N2O), but little is known about these gases emissions as affected by aquaculture species, stocking and water management in aquaculture ponds. Here, a two-year study was carried out to quantify CH4 and N2O emissions from freshwater crab and fish aquaculture ponds in subtropical China. We further explored how the microbial functional genes [CH4: mcrA and pmoA; N2O: archaeal and bacterial amoA (AOA + AOB), nirS, nirK, nosZ] may drive CH4 and N2O release in the crab aquaculture pond typically undergoing flooding-to-drainage alteration. Over the two-year period, annual CH4 and N2O fluxes averaged 0.95 mg m−2 h−1 and 20.94 μg m−2 h−1 in the fish aquaculture, and 0.78 mg m−2 h−1and 28.48 μg m−2 h−1 in the crab aquaculture, respectively. The direct N2O emission factors were estimated to be 0.77% and 0.36% of the total N input by feed or 1.59 g N2O-N kg−1 and 1.06 g N2O-N kg−1 aquaculture yield in the crab and fish ponds, respectively. Among three functional stocking areas, CH4 and N2O emissions were consistently the highest at the feeding area (FA) in the both aquaculture ponds, followed by at the undisturbed area (UA) and aerated area (AA). The shift in sediment soil moisture from waterlogging to drainage conditions significantly increased the abundance of AOB relative to AOA and pmoA, decreased those of denitrifying functional genes (nirS, nirK, nosZ) and mcrA, while did not alter the functional group ratio of nirS + nirK relative to nosZ. Our results highlight that a better understanding of CH4 and N2O emissions from aquaculture ponds requires taking into consideration of data sourced from more diverse aquaculture systems with different management patterns. In addition, a deep analysis of the microbial processes that drive CH4 and N2O production and consumption from aquaculture ponds remains to be addressed in future studies.

The deposition is an important process of microplastics transporting from atmosphere to water and soil. But the spatial and temporal distribution of microplastics in urban atmospheric deposition and its influencing factors are poorly understood. The current study investigated the possible sources, spatial and temporal distribution, and potential ecological risk of microplastics in deposition from the valley basin of Lanzhou city during the COVID-19 pandemic (from February to August, 2020). The deposition flux of microplastics was 353.83 n m

Background Cerebral ischemia-reperfusion injury (CI/R) is among the most common diseases affecting the central nervous system. Due to the poor efficacy and adverse side effects of the drugs used to treat CI/R in clinical trials, a new treatment strategy is urgently needed. In this study, we aimed to investigate whether miR-103a-3p alleviates CI/R in vivo and vitro and to explore the relevant mechanisms. Methods BV2 microglial cells underwent oxygen-glucose deprivation (OGD) treatment to imitate the pathophysiology of CI/R in vitro. A middle cerebral artery occlusion (MCAO) rat model was established to imitate the pathophysiology of CI/R in vivo. The expression levels of miR-103a-3p and HMGB1 were detected by reverse transcription-polymerase chain reaction (RT-PCR) and western blot. Flow cytometry, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay, enzyme-linked immunosorbent assay (ELISA), and hematoxylin and eosin (H&E) and Nissl staining were used to evaluated apoptosis, oxidative stress, inflammatory response, and histopathology, respectively. Results OGD-stimulated BV2 microglial cells and brain tissues with CI/R had low expression of miR-103a-3p but high expression of high mobility group box 1 (HMGB1). As expected, miR-103a-3p and HMGB1 had a targeting relationship. Overexpression of HMGB1 enhanced the the levels of interleukin (IL)-1 beta, tumor necrosis factor-alpha (TNF-α) and malondialdehyde (MDA), but reduced the content of superoxide dismutase (SOD), IL-4, and IL-10, in vitro. Moreover, high expression of HMGB1 aggravated the brain injury of the model rats, and increased the secretion of inflammatory factors, exacerbated oxidative stress, and further induced tissue apoptosis in the brain tissue. Importantly, these effects of HMGB1 overexpression were partly reversed by miR-103a-3p overexpression on HMGB1 interference. Conclusions HMGB1 is targeted by miR-103a-3p, which may be a new strategy in the treatment of CI/R.

As global communities respond to the spread of coronavirus disease 2019 (COVID-19), urban residents worldwide have reduced their mobility, which may have incidentally kept people away from greenspaces. Surprisingly, anecdotal evidence suggests greenspace use surged in Asian cities. In this study, we used the COVID-19 pandemic as a natural experiment to investigate individuals' behavioral changes in greenspace use before and during the pandemic. We created a longitudinal panel dataset comprising Instagram posts from 100,232 users relating to 1185 greenspaces in four Asian cities: Hong Kong, Singapore, Tokyo, and Seoul. We found a 5.3% increase in the odds of people using greenspaces for every 100-case increase in weekly new cases. The models also revealed that people prefer nature parks that are large and close to city centers. In summary, because of the established physical and mental health benefits of greenspaces, people have been escaping to nature to cope with the pandemic in Asian cities., Graphical abstract Unlabelled Image

This paper describes a method for calibrating binary Cryogenic Current Comparator(CCC) winding ratios. The method, described as a step-up technique, involves calibrating the CCC winding first on a 1:1 ratio. By adding an additional 1-turn as a reference, the comparison of two 1-turn windings can be realized, then the two 1-turn windings are added and compared to the 2-turns winding. This process continues until the $2^{n}$ -turns winding is checked. The CCC ratio error and its uncertainty are also analyzed in this paper. Preliminary experiment shows that the ratio $400(2^{8}+2^{7}+2^{4}): 4(2^{2})$ error is below 5 part in 1011.

Different from the noise thermometer in a substitution configuration, a superposition configuration allows a reference signal to be injected into the sense resistor so that the thermal voltage noise and the reference signal can be simultaneously transferred to the measurement electronics through the same transmission line. The construction of a quantum-voltage-calibrated superposition noise thermometer is presented in this paper and preliminary experiments are conducted to demonstrate its feasibility for temperature measurements. A polynomial fitting is used to fit the transfer function of the connection network between the QVNS and the sense resistor.

The experiments were carried out aimed to compare the capacitance measured in terms of the new calculable capacitor standard to the capacitance measured in terms of the von Klitzing constant ( $R_{\mathrm{K}}$ ) using the quantized Hall resistance (QHR). The experiment systems such as the calculable capacitor, the quantized Hall resistance standard, and the impedance measurement chain are briefly presented. The recent two key comparison results on capacitance and resistance standards are also introduced.

Background: We used the first metro system in a developing city as a natural experiment to investigate the causal inference in the new metro’s impact on modal shift and active travel. Material and methods: The treatment group was formed by residents from neighbourhoods located within the 800-m walking distance to new metro stations. The first control group was formed by residents lived 1.6 km away from and outside of walking distance to the nearest station, and the second was 5 km away and outside of cycling distance. The groups were determined by local transit-oriented planning practice and empirical studies on active travel. Of the 5627 participants who had finished a baseline travel behaviour survey before new metro launched, 1770 returned and completed the follow-up survey a year after the metro’s operation, which consists of 833 cohort participants in the treatment group and 937 in the two types of control groups. We used a difference-in-difference method to make before and after comparisons of travel behaviour changes between treatment and control groups. Results: Our longitudinal data analyses revealed diverse travel behaviour changes. In general, people who used to take bus have adopted metro. The average metro usage was 30.9 (28.8–33.3) minutes daily for work trips and 16.6 (14.9–18.7) minutes daily for non-work trips. Walking time decreased 19.7 minutes at most (p

Measuring Variable-frequency big current has a great technical difficulty, you first need transfer Variable-frequency big current to small current is easy to measure, and then transfer variable frequency small current to a voltage. In this paper we uses a zero flux current transformer transfer high current into a small current, after then use a shunt transfer alternating current to a variable frequency voltage, realizing high accuracy variable-frequency big current calibration, measurement uncertainty up to 1×10-4,which can meet the needs of the current calibration,it has been used in many project, and achieved good results.

After the continual investigation on the electrical compensation method for the end effect, the optimal hollow active auxiliary electrode (OHAAE) has been successfully developed and substituted for the current nosepiece in the new vertical calculable capacitor (CC) at NIM. Applying the best compensation voltage of ${U_{\text{best}}}$ obtained from the model tests, the initial measurement result by the OHAAE in the new vertical CC for reproducing the 1 pF capacitance of the same commercial capacitor agrees with that by the nosepiece in the level of ${6.0\times 10^{-9}}$ .

This paper describes the progress on a new measurement of von Klitzing constant $\pmb{(R_{\text{k}})}$ through an experiment linking the new calculable capacitor and the quantized Hall resistance by means of a quadrature transfer at NIM. The recent improvements of the new calculable capacitor, the optical interferometry, the impedance measurement chain are presented.

This paper describes an absolute method for calibrating commercial 1000:1 DC current transducers (DCCTs). By adding two auxiliary windings to produce 10:1 and 100:1 ratios, we use a three-step build-up method to establish the 1000:1 current ratio standard. First, we determine the 10:1 ratios of 11 DCCTs through permutation; second, we set up a two-stage composite DCCT to produce a 100:1 ratio; after switching auxiliary windings in the two-stage setup, we then derive the 1000:1 current ratio. The experimental results will be presented during the conference.

As a key instrument for resistance metrology, cryogenic current comparator (CCC) is now widely used in national labs. In order to further improve the performances of CCC and make it easy operate, NIM has made some improvements, which are developing digital controller to replace conventional analog circuit and designing a zero boil-off cryogenic container specially served for CCC. Pre-experiments show that the new digital controller performs a better operability and the zero boil-off cryogenic container has a significant convenience for CCC cryo maintenance.

To compensate the end effect error in a vertical calculable cross capacitor with a fixed and a movable guard electrode, two different methods, a nosepiece and a modified active auxiliary electrode, are usually adopted at National Measurement Institutes across the world. However, the latter electrical approach can be more difficult when assembling the mirrors in the resonant cavity of the Fabry–Perot laser interferometer. This paper describes a novel hollow active auxiliary electrode that can satisfy the optical requirements. The model test experimental results show that it has the same or better compensation effectiveness for the end effect error in comparison with the modified active auxiliary electrode.

A new type of calculable capacitor was initially built at the National Institute of Metrology, China, in cooperation with the National Measurement Institute, Australia. The capacitor realized the SI unit of capacitance at 1 pF, with an uncertainty of 20 parts in $10^{9}$ . A simplified operational approach was used that avoids the complex substitution measuring process with small-value capacitors. The details of novel aspects of the installation and adjustment processes are presented, together with the experimental results and an initial uncertainty estimation.

A digital impedance bridge with auto-balancing source ratio is described in this summary paper. Unlike impedances can be compared in audio frequency range with arbitrary magnitude and phase ratio produced by two digital generators. An automatic source balance method is introduced to the bridge with no need for fine adjustment of the complex source ratio and faster balancing of the bridge. The synchronous sampling method is adopted to measure the complex ratio at different frequency in normal conditions. Preliminary tests on L-R comparison were carried out.

Oxidized low-density lipoproteins (ox-LDL) play a critical role in endothelial injury including cytoskeleton reorganization, which is closely related to actin-related protein 2/3 (Arp2/3) complex. The aim of this study was to investigate the role of Arp2/3 complex in ox-LDL-induced endothelial dysfunction. In this study, we found that Arp2 and Arp3 expression was increased under atherosclerotic conditions both in ApoE−/− mice and in ox-LDL-stimulated human coronary artery endothelial cells (HCAECs). Arp2/3 complex inhibitor CK666 significantly reduced ox-LDL-induced ROS generation and cytoskeleton reorganization, and increased NO release in HCAECs. Pretreatment with LOX-1- but not CD36-blocking antibody markedly decreased ox-LDL-induced Arp2 and Arp3 expression. Moreover, Rac-1 siRNA remarkably suppressed ox-LDL-stimulated Arp2 and Arp3 expression. Additionally, CK666 reduced endothelial nitric oxide synthase (eNOS) expression and atherosclerotic lesions in ApoE−/− mice. Collectively, ox-LDL induces endothelial dysfunction by activating LOX-1/Rac-1 signaling and upregulating Arp2/3 complex expression.

The precise dc-based measurement of the mutual inductance is one of the key issues in the Joule Balance method used to determine Planck's constant h. Here, a new compensation method with a standard square wave is provided. The dc value of the mutual inductance is obtained by measuring the integral area of the induced voltage. To increase the accuracy of this integral method, we just accurately measure the residual area observed between the induced voltage of the mutual inductor and a synchronously generated standard square wave. Experimental results indicate that this approach is consistent with the previous frequency extrapolation method within 1 ppm. The measurement uncertainty is estimated to be about 0.22 μH/H for the 340-mH mutual inductor at room temperature. A better result of 0.1 ppm could be obtained when the superconducting coil is used.

The precise measurement of Planck constant h to establish a kind of quantum mass standard is an important but very difficult work. The Joule Balance method, for the same purpose but different from Watt Balance method, has been going on at the National Institute of Metrology for three years. All the measurements were carried out in the atmosphere of an air-conditioned room. The uncertainty is several parts in 104 (k=1) and expected to be improved when superconducting coils and other approaches are used further. The principle and progress are described here.

In order to precisely measure the displacement of the coil suspension system of the Joule Balance in the static state, we give a detailed analysis about its influence factors in this paper. We designed a dual-frequency laser interferometer system to measure the movement of the coil suspension in vertical direction. And a supporting device was designed to support the coil for the aim to make it more stable. The result showed that the coil suspension system is affected by ground vibration, temperature drift, stress release, pendulum swing. The drift of the coil suspension is about 120nm among 3 minutes without supporting device, the data is greatly reduced after we support it.

We present in CPEM 2012 the latest quantum Hall (QH) experimental results of GaAs-AlGaAs Hall devices fabricated by NIM. AuGeNi and In are utilized as the contacts material. Precision measurement indicates quantized Hall devices with low contact resistance and good breakdown current are obtained.

In this paper an improved bootstrap method used for the calibration of inductive voltage dividers(IVDs) is described which uses a special constructed reference transformer to decrease the system errors due to the screen current. The reference transformer is wound with a triaxial cable which was divided into two equal lengths by a break in the both of the outers. A initial measurement result shows that the error introduced by the changes of the reference voltage ratio is less than 1nV/V at 1592Hz by using this reference transformer.

A two terminal-pair coaxial AC bridge is constructed at NIM for high precision capacitance transfer, in which, an auto auxiliary source balance method is proposed and achieved. The error introduced by auto source balance circuit is at negligible level. The bridge can transfer capacitance from 1 pF to 100 pF with an uncertainty of 1 × 10−8 (k = 1) at low audio frequency.

This paper describes the design, schematics, and performance of a very low-noise J-EFT preamplifier. The amplifier has a gain flatness better than 1dB in the 500Hz to 1MHz frequency region. Noise measurements on this amplifier yield a voltage noise less 0.5nV/√Hz and current noise less 1fA/√Hz in the 100Hz to 100kHz frequency region. It could be used as the preamplifier of the null detector of AC bridges. With modest changes it could be extended to a wide variety of uses requiring low noise gain.

The motion character of a special three degree-of-freedom (DOF) parallel mechanism is analyzed by screw theory. This mechanism’s significant feature is that the axis of its prismatic pair is parallel to that of its revolute pair in the same limb. Firstly, by analysis, the mechanism’s constraint screws are obtained, which leads to motions along the fixed-length links being restricted. Secondly, we get the mechanism’s constraint screws’ reciprocal productions, namely the mechanism’s free motions, which are three screw motions. After that, a numerical example is presented to illustrate the analysis in detail. At last, we draw some conclusions and discuss the future work.

Traditionally, the most precise way to get the mutual inductance value is by a Campbell calculable mutual inductor. Here, an approach of measuring the mutual inductance at low frequency with compensation method is described. A multi-channel direct digital frequency synthesis source is developed to provide stable and precise phase. The mutual inductance is traced to the value of the frequency and resistance directly. The measurement uncertainty is 0.43 ppm at present and could be improved further.