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Background: During the research phase of acrylic panel for the Jiangmen Underground Neutrino Observatory (JUNO) central detector (CD), the darkroom transmittance measurement system (DTMS) was designed and built, and a massive amount of measurements were carried out to help determine the composition and processing techniques of the acrylic panel. Motivation: The mass production of acrylic panels was started after the pilot production. The requirement of transmittance measurement put forward new demands on operation, and a new measurement system was considered to support removable and non-destructive measurement on site. Result: After the accomplishment of design, development and verification were completed, the laser measurement system came into use in the acrylic workshop of Taixing Donchamp Acrylic Ltd, and the transmittance results of acrylic spherical panels met the requirement of JUNO. The optical design, tooling design, data processing interface and uncertainty analyses of the laser measurement system are discussed in detail, and the measured transmittance results are also introduced in this article.

The sensing performance of gas sensors is determined by three key factors of sensing, transducing and utilization ratio of sensing body. However, these three factors are structurally and functionally independent for most existing gas sensors, restricting the integration and multi-functionalization of the gas discrimination. Herein, we reported a ternary ordered assembly strategy to synchronously and sympatrically integrate and optimize the three key factors in one single device. The in-situ polymerized Ppy coating serves as the sensing component while the embedded PZT nanofiller functions as transducing element, where the utilization ratio of sensing body is directly regulated by the porosity and sensing coating thickness via controlling the sugar granule loading amount and polymerization time. By tuning in-situ polymerization quantity, sacrificial templating amount and transducing loading as well as poling time, an optimal ammonia sensing response was accomplished with a responsivity of 387% at the 100 ppm, a sensitivity of 4.29% ppm−1, excellent selectivity and long-term stability. A theoretical gas-sensitive model was established by combining the experimental characterization with finite element calculation and phase-field simulation. This work throws lights on the fundamental gas sensing mechanism and provides a promising paradigm for developing multi-level controllable sensing devices for physiological assessment and environmental monitoring.

The Jiangmen Underground Neutrino Observatory (JUNO) is a multipurpose neutrino experiment designed to determine neutrino mass hierarchy, precisely measure oscillation parameters and study solar neutrinos, supernova neutrinos and geo-neutrinos. The JUNO Central Detector 20 kton liquid scintillator target mass is contained by a huge acrylic sphere with a 35.4 m inner diameter, supported by a stainless steel structure, and the sphere is eventually submerged in pure water. Before the JUNO Central Detector is built, a small prototype has been designed and static loading experiments will be carried out to verify the consistency of the finite-element calculations and static loading experiments and test the subsystems performances, such as the monitoring system and liquid scintillator filling system. The small prototype is composed of an acrylic sphere with a 3 m inner diameter and an aluminum alloy support structure. In this article, the structure of the small prototype is briefly described. A detailed simulation study using finite element analysis is conducted to account for liquid-filled condition, temperature variation and existence of high load (due to vacuum pumping) and demonstrate a satisfying mechanical performance of the small prototype. The experimental plan about the prototype on the basis of the simulation will also be mentioned.

Purpose: In response to the government’s decision to make “entrepreneurship and innovation for all” a national strategy in its 2015 annual work report, Chinese professionals in the library field have expressed a growing interest in makerspaces. This study aims to provide an overview of their current research studies and attempts in constructing makerspaces. Design/methodology/approach: The authors aggregated research materials on library makerspaces in China from two sources: journal articles from the China National Knowledge Infrastructure Database and online news reports from the search engine Baidu.com. Content analysis was used to extract information regarding visions and perceived values, service models and technology adoption. Findings: While a growing number of Chinese academic publications are concerned with library makerspaces, the existing research focuses on foreign cases and offers few empirical studies on domestic application scenarios. Libraries and researchers in China hold a positive and supportive attitude toward makerspaces. 3D printing is the most frequently mentioned technology, and free-to-use, promoting communication and realization of ideas and dreams are the most emphasized values. Libraries should highlight their own unique advantages and tap into their resources and services in mutually beneficial collaborations with other types of makerspaces. Research limitations/implications: First, the results of this study cannot fully summarize the development status of makerspaces in Chinese libraries. Second, the research materials used in this study may be biased, especially the news reports. Practical implications: This paper presents a semantic, visualized analysis of aggregated online news articles and journal articles on library makerspaces in China in an attempt to summarize their characteristics and guiding values, validate the advantages of library makerspaces and give suggestions on improving their service models. Social implications: This paper introduces the development trend of makerspace in Chinese libraries, so that researchers at home and abroad can learn more about the development of Chinese library. Originality/value: This study comprehensively overviews the development of library makerspaces in China. The results provide suggestions to improve maker services in library.

The organic compound 2,5-furandicarboxylic acid (FDCA) has been identified by the US Department of Energy (DOE) as a valuable platform chemical for a wide range of industrial applications. Currently, the most popular route for FDCA synthesis is reported to be the oxidation of 5-hydroxymethylfurfural (HMF) by O2over the catalysis of noble metals (e.g., Au, Pt, Ru, and Pd). However, the high costs of noble metal catalysts remain a major barrier for producing FDCA at an industrial scale. Herein, we report a transition metal-free synthesis strategy for the oxidation of HMF to FDCA under O2or ambient air. A simple but unprecedented process for the aerobic oxidation of HMF was carried out in organic solvents using only bases as the promoters. According to the high performance liquid chromatography (HPLC) analysis, excellent product yield (91%) was obtained in the presence of NaOH in dimethylformamide (DMF) at room temperature (25 °C). A plausible mechanism for the NaOH-promoted aerobic oxidation of HMF in DMF is also outlined in this paper. After the reaction, the sodium salt of FDCA particles were dispersed in the reaction mixture, making it possible for product separation and solvent reuse. The new HMF oxidation approach is expected to be a practical alternative to current ones, which depend on the use of noble metal catalysts.

In order to improve the charged particle identification capability, end-cap time-of-flight (ETOF) detector of the Beijing Spectrometer (BESIII) has been upgraded with multi-gap resistive plate chamber (MRPC) technology, aiming at an overall time resolution of 80 ps for minimum-ionization particles to extend the K/$$\pi $$ π separation (2$$\sigma $$ σ ) momentum range to 1.4 GeV/c. The previous version of ETOF in BESIII consisted of plastic scintillators. The multi-hit events distort both shape and amplitude of the output signals. MRPC technique was chosen for the BESIII ETOF upgrade as it provides high time resolution and high detection efficiency, is of relatively low cost and is insensitive to neutral particles. Most importantly, the fine segmentation of the MRPC readout stripes can suppress multi-hit events effectively. The final design of MRPC module for ETOF is characterized by double-stack (2$$\times $$ × 6) structure, dual-end readout mode and precision electronics. To batch-produce and test these MRPC modules, a series of tools and production procedures as well as related performance simulation and test methods were developed. Results showed that each MRPC module’s intrinsic time resolution (including the electronics contribution) is around 50 ps and the efficiency is better than 97%. The overall performance of the upgraded ETOF is better than the designed index. The new ETOF has been successfully installed at BESIII and run in 2016.

Piezo-potential promoted photocatalysis enables a scalable and high-efficiency dye decomposition by conjugating the photoexcitation and mechanical stimulus. However, its catalytic efficiency is significantly restricted by the limited quantum yield and piezoelectric activity of catalysts. Herein, a heterogeneous CdS-Au composite photocatalyst was synthesized via a facile water bath heating and reflux condensation method for organic pollutants degradation. The synergism between piezo-phototronic effect and localized surface plasmon resonance facilitates photon-generated carrier separation and internal quantum efficiency. The loading of Au nanoparticles remarkably modulates the morphologies, surface defect, effective optronics utilization and photocatalytic activities of CdS nanospheres. A 2.3 folds enhancement in the photodegradation of Methyl Orange (MO) was observed with the optimal 4 mol% Au loading. Furthermore, the impact of frequency and intensity of ultrasonication on the electrochemical impedance and photocatalytic activity was systematically investigated. This work offers a promising approach for harnessing noise or vibration for environmental remediation and opens up a new route for designing and developing high-performance piezo-photocatalyst.

Crude glycerol, a low-value by-product from the biodiesel industry, has a significantly different composition compared to pure glycerol. Generally, crude glycerol contains various impurities, such as methanol, water, soap, free fatty acids, fatty acid methyl esters, and glycerides. In this study, waterborne polyurethane (WPU) coatings were prepared from crude glycerol-based polyols synthesized via a one-pot thermochemical conversion of crude glycerol. The corrosion properties of the coatings were characterized by electrochemical impedance spectroscopy, polarization measurements, and salt spray testing. The preliminary results showed that crude glycerol-based WPU coatings had a considerably enhanced corrosion resistant performance on metallic substrates.

The metal sealing performance of subsea X-tree wellhead connectors is crucial for the safety and reliability of subsea X-trees. In order to establish the theoretical relation between metal sealing ring’s contact stress and its structural parameters and working pressure, a mechanical analysis method for double-cone sealing of high pressure vessels is applied in analyzing the metal sealing ring under the condition of preload and operation. As a result, the formula of the unit sealing load for the metal sealing ring under operation with residual preload is shown in this paper, which ensures that the metal sealing ring has an excellent sealing effect and can prevent the metal sealing ring from yielding. Besides, while analyzing the sealing process of the metal sealing ring, the change rule of contact stress and working pressure is concluded here, putting forward that the structural parameters of the metal sealing ring are the major factors affecting the change rule. Finally, the analytical solution through theoretical analysis is compared with the simulation result through finite element analysis in a force feedback experiment, and both are consistent with each other, which fully verifies for the design and calculation theory on metal sealing ring’s contact stress and its structural parameters and working pressure deduced in this paper. The proposed research will be treated as an applicable theory guiding the design of metal seal for subsea X-tree wellhead connectors.

The antineutrino detectors for the Daya Bay reactor neutrino experiment are liquid scintillator detectors designed to detect electron anti-neutrino via inverse beta interactions with high efficiency and low backgrounds. Since the antineutrino detector will be installed and immerged in water Cherenkov detector and will run for 3 to 5 years, water tightness is critical to the successful operation of the antineutrino detectors. A special seal technique was used for this purpose. Three leak checking methods have been employed to ensure the seal quality. This paper describes the sealing method and leakage testing results.The antineutrino detectors for the Daya Bay reactor neutrino experiment are liquid scintillator detectors designed to detect electron anti-neutrino via inverse beta interactions with high efficiency and low backgrounds. Since the antineutrino detector will be installed and immerged in water Cherenkov detector and will run for 3 to 5 years, water tightness is critical to the successful operation of the antineutrino detectors. A special seal technique was used for this purpose. Three leak checking methods have been employed to ensure the seal quality. This paper describes the sealing method and leakage testing results.

NiWO4microflowers with a large surface area up to 79.77 m2·g–1are synthesized in situ via a facile coprecipitation method. The NiWO4microflowers are further decorated with multi-walled carbon nanotubes (MWCNTs) and assembled to form composites for NH3detection. The as-fabricated composite exhibits an excellent NH3sensing response/recovery time (53 s/177 s) at a temperature of 460 °C, which is a 10-fold enhancement compared to that of pristine NiWO4. It also demonstrates a low detection limit of 50 ppm; the improved sensing performance is attributed to the porous structure of the material, the large specific surface area, and the p–n heterojunction formed between the MWNTs and NiWO4. The gas sensitivity of the sensor based on daisy-like NiWO4/MWCNTs shows that the sensor based on 10 mol % (MWN10) has the best gas sensitivity, with a sensitivity of 13.07 to 50 ppm NH3at room temperature and a detection lower limit of 20 ppm. NH3, CO2, NO2, SO2, CO, and CH4are used as typical target gases to construct the NiWO4/MWCNTs gas-sensitive material and study the research method combining density functional theory calculations and experiments. By calculating the morphology and structure of the gas-sensitive material NiWO4(110), the MWCNT load samples, the vacancy defects, and the influence law and internal mechanism of gas sensitivity were described.

Introduction: The Jiangmen Underground Neutrino Observatory (JUNO) is a multipurpose neutrino experiment designed to determine neutrino mass hierarchy, precisely measure oscillation parameters and study solar neutrinos, supernova neutrinos and geo-neutrinos, etc. The central detector (CD) of JUNO has 20,000 tons liquid scintillator as target mass, which contains inside a huge acrylic sphere with inner diameter of 35.4 m, supported by a stainless steel structure. The whole structure of CD will be installed inside a cylindrical water pool, and the acrylic sphere will be submerged in the center of water pool. The operating temperature of CD is designed to be 21 °C as long as over 20 years, which is determined by the mechanical requirement of the structure and physics consideration. Methods: For this operating temperature, a special cooling system will be used to maintain the temperature inside the water pool. The main structure of CD is composed of acrylic and stainless steel, and they have much different thermal expansion coefficients, strengths and life times. Change in temperature may affect the safety of CD. As part of reliability analysis, the effect of cooling system failure on the CD is considered, and finite element method is used in our thermal calculation. In this article, the temperature fields before and after cooling system failure are calculated and analyzed, and the temperatures of different locations of water pool after cooling system failure are compared and discussed in detail.

Crude glycerol, a low-value by-product from the biodiesel industry, has a significantly different composition compared to pure glycerol. Generally, crude glycerol contains various impurities, such as methanol, water, soap, free fatty acids, fatty acid methyl esters, and glycerides. In this study, waterborne polyurethane (WPU) coatings were prepared from crude glycerol-based polyols synthesized via a one-pot thermochemical conversion of crude glycerol. The corrosion properties of the coatings were characterized by electrochemical impedance spectroscopy, polarization measurements, and salt spray testing. The preliminary results showed that crude glycerol-based WPU coatings had a considerably enhanced corrosion resistant performance on metallic substrates.

Crude glycerol (CG), a low-value byproduct from the biodiesel industry, has a significantly different composition compared to pure glycerol. Generally, crude glycerol contains various impurities, such as methanol, water, soap, free fatty acids (FFAs), fatty acid methyl esters (FAMEs), and glycerides. In this study, crude glycerol-based waterborne polyurethane (WPU) coatings were prepared from polyols synthesized using crude glycerol as a sole feedstock via a thermochemical conversion process. The corrosion properties of coatings were characterized by electrochemical impedance spectroscopy (EIS), polarization measurement and salt spray test. The initial experimental results show that crude glycerol-based WPU coatings have a considerably enhanced corrosion resistant performance of metallic substrate.