23 research outputs found

    Experimental Investigations and Field Applications of Chemical Suppressants for Dust Control in Coal Mines

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    It is known that high dust concentrations are severely hazardous to health of miners and the safe operations of coal mines. The results of the suppressions of coal dust via chemical dust suppressant methods have been of critical significance, and these methods have been widely applied in coal mines. In this research study, a type of complex dust suppressant composed of surfactants, synergists, and cellulose was prepared. The prepared suppressant was characterized by a high wetting ability and adhesive capacity. The results of the performance tests of this study’s proposed complex dust suppressant showed that its dust sedimentation time was only four seconds, which was observed to be much shorter than that of water alone. Also, the proposed suppressant displayed a viscosity which was 25 times that of water. In this study’s field tests, the proposed complex dust suppressant was used for dust control in a mining roadway of the Zhangcun Coal Mine. The field test results revealed that the average suppression efficiencies of the total dust and respirable dust had reached 89.2% and 87.7%, respectively. Furthermore, a 44.5% increase in the control of the total dust had been observed, and a 65.6% increase in the control of the respirable dust had been achieved with the proposed method, when compared with the results of the previously used water curtain technology

    Thermally Activated Persulfate (TAP) Oxidation of Antiepileptic Drug Carbamazepine in Water

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    Sulfate radicals-based advanced oxidation processes have been applied in water treatment and in situ chemical oxidation. Batch experiments were conducted to investigate the influencing factors including persulfate dosage, initial carbamazepine (CBZ) concentrations, solution pH, coexisting inorganic anions and cations on the decomposition of CBZ using thermally activated persulfate (TAP) technology. The results showed that TAP oxidation was efficient process for the CBZ degradation in water. The generation of sulfate radicals was accounted for the CBZ degradation in TAP system. The CBZ degradation rate constant increased as persulfate dosage increased and decreased as the initial CBZ concentrations increased. The CBZ decomposition rate decreased with the increasing pH and the best degradation occurred at pH 3. The exception was the strong alkaline condition under which a higher CBZ degradation performance was achieved. Coexisting inorganic anions slowed down the CBZ degradation to different degrees and the inhibiting effect abided by the following order: CO32→HCO3→Cl→SO42→NO3-. In contrast, coexisting cations could significantly enhance the CBZ degradation, and the promoting effect was in the order of Fe2+Cu2+Fe3+. In this study, six major intermediate products were generated during the TAP oxidation

    Effects of Different Algaecides on the Photosynthetic Capacity, Cell Integrity and Microcystin-LR Release of Microcystis Aeruginosa

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    Bench scale tests were conducted to study the effects of four common algaecides, including copper sulfate, hydrogen peroxide, diuron and ethyl 2-methylacetoacetate (EMA) on the photosynthetic capacity, cell integrity and microcystin-LR (MC-LR) release of Microcystis aeruginosa. The release of potassium (K + ) from cell membrane during algaecide exposure was also analyzed. The three typical photosynthetic parameters, including the effective quantum yield (F e ), photosynthetic efficiency (α) and maximal electron transport rate (rETR max ), were measured by a pulse amplitude modulated (PAM) fluorometry. Results showed that the photosynthetic capacity was all inhibited by the four algaecides, to different degrees, by limiting the energy capture in photosynthesis, and blocking the electron transfer chain in primary reaction. For example, at high diuron concentration (7.5mgL -1 ), F e , α and rETR max decreased from 0.46 to 0.19 (p\u3c0.01), from 0.20 to 0.01 (p\u3c0.01) μmol electrons m -2 s -1 /μmol photons m -2 s -1 , and from 160.7 to 0.1 (p\u3c0.001) μmolm -2 s -1 compared with the control group after 96h of exposure, respectively. Furthermore, the increase of algaecide dose could lead to the cell lysis, as well as release of intracellular MC-LR that enhanced the accumulation of extracellular MC-LR. The order of MC-LR release potential for the four algaecides was CuSO 4 \u3eH 2 O 2 \u3ediuron\u3eEMA

    Multiwalled Carbon Nanotubes as Adsorbents for Removal of Herbicide Diuron from Aqueous Solution

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    The adsorption of diuron onto as-prepared and oxidized multiwalled carbon nanotubes (MWCNTs) from aqueous solution has been studied through batch experiments, in which the effect of contact time, temperature, pH and coexisting Cu 2+ were investigated. The adsorption performance of diuron onto MWCNTs fitted the pseudo-second-order model and apparent equilibrium was reached within 1h. The experimental data showed good correlation with Freundlich, Langmuir and Polanyi-Manes models in the range of experimental concentrations, but followed Polanyi-Manes model most appropriate. The calculated thermodynamic parameters showed adsorption of diuron onto MWCNTs was exothermic and spontaneous. Except for the introduction of oxygen-containing functional groups onto the surfaces of MWCNTs, the oxidized treatment of as-prepared MWCNTs can also increase the surface area and the pore volume, which resulted in the increase adsorption of diuron in this study. The adsorption of diuron was found to be pH dependent, and more adsorption was observed under neutral and basic conditions. The presence of Cu 2+ has no significant effect on the adsorption of diuron onto as-prepared MWCNTs, on the contrary, the presence of Cu 2+ can greatly decrease the adsorption of diuron onto oxidized MWCNTs. In addition, competitive adsorption was greater at higher than at lower diuron concentrations

    Characterization of Algal Organic Matters of Microcystis Aeruginosa: Biodegradability, DBP Formation and Membrane Fouling Potential

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    Algal organic matters (AOM), including extracellular organic matters (EOM) and intracellular organic matters (IOM), were comprehensively studied in terms of their biodegradability, disinfection byproduct (DBP) formation potentials and membrane fouling. EOM and IOM were fractionated into hydrophobic (HP), transphilic (TP) and hydrophilic (HL) constituents. The HP, TP and HL fractions of EOM and IOM were highly biodegradable with BDOC/DOC ranging from 52.5% to 67.4% and the DBP formation potentials followed the order of HP \u3e TP \u3e HL, except of IOM-HL. Biodegradable process proved very effective in removing the DBP formation potentials. Moreover, the AOM characteristics were also evaluated during ultrafiltration (UF) treatment. Results demonstrated that UF favourably remove DOC and DBP formation potential of IOM than those of EOM. And the HL constituents played a more important role in membrane fouling than HP and TP. The UF foulants exhibited higher BDOC/DOC than AOM, suggesting EOM and IOM might enhance biofouling because more biodegradable proteins and polysaccharides were found in membrane foulants. Therefore, appropriate biological treatment, ultrafiltration, or combination of the both are potential options to address these algae-caused water quality issues

    Low-temperature sintering of silver-ammonia complex organic composite ink shows high conductivity for humidity sensors

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    The development of flexible electronic devices is faced with the challenge of difficult fabrication of complex functional structures on flexible substrates. In this paper, a high viscosity ink of silver-ammonia complex was developed based on the reductive ink principle. Using the electrohydrodynamic direct writing, composite fiber patterned printing was achieved on a flexible substrate. By low-temperature sintering of precursor fibers for reduction, a dense silver structure was formed on the surface, resulting in the formation of Ag/PEO conductive fibers. This approach avoided the high temperature damage to the flexible substrate and the adhesion of materials, while demonstrating good conductivity. The Ag/PEO conductive fibers exhibited different sensitivities to H2O molecules in low, medium, and high humidity environments, which were used to design a flexible Ag structure humidity sensor (ASHS) as a functional material. The ASHS showed a linear response relationship and a fast response speed in an environmental humidity range of 11 % to 75 %RH, enabling real-time monitoring of human respiration. This study demonstrates a promising application prospect of the silver-ammine complex ink in the field of flexible electronic devices

    Developmental and reproductive toxicity of a recombinant protein subunit COVID-19 vaccine (ZF2001) in rats

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    Abstract ZF2001, a protein subunit vaccine against coronavirus disease 2019 (COVID-19), contains recombinant tandem repeat of dimeric receptor-binding domain (RBD) protein of the SARS-CoV-2 spike protein with an aluminium-based adjuvant. During the development of this vaccine, two nonclinical studies were conducted to evaluate female fertility, embryo-fetal development, and postnatal developmental toxicity in Sprague‒Dawley rats according to the ICH S5 (R3) guideline. In Study 1 (embryo-fetal developmental toxicity, EFD), 144 virgin female rats were randomly assigned into four groups and received three doses of vaccine (25 μg or 50 μg RBD protein/dose, containing the aluminium-based adjuvant), the aluminium-based adjuvant or a sodium chloride injection administered intramuscularly on days 21 and 7 prior to mating and on gestation day (GD) 6. In Study 2 (pre- and postnatal developmental toxicity, PPND), ZF2001 at a dose of 25 μg RBD protein/dose or sodium chloride injection was administered intramuscularly to female rats (n = 28 per group) 7 days prior to mating and on GD 6, GD 20 and postnatal day (PND) 10. There were no obvious adverse effects in dams, except for local injection site reactions related to the aluminium-based adjuvant (yellow nodular deposits in the interstitial muscle fibres). There were also no effects of ZF2001 on the mating performance, fertility or reproductive performance of parental females, embryo-fetal development, postnatal survival, growth, physical development, reflex ontogeny, behavioural and neurofunctional development, or reproductive performance of the offspring. The strong immune responses associated with binding and neutralising antibodies were both confirmed in dams and fetuses or offspring in these two studies. These results would support clinical trials or the use of ZF2001 in maternal immunisation campaigns, including those involving women with childbearing potential, regardless of pregnancy status

    Facile Preparation of AIE-Active Fluorescent Nanoparticles through Flash Nanoprecipitation

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    Flash nanoprecipitation (FNP) is an easily scalable and fast processing method for the preparation of nanoparticles (NPs) with simple vortex equipment. By using the FNP method, fluorescent NPs are prepared in less than 1 s in a multi-inlet vortex mixer, in which hydrophobic aggregation-induced emission (AIE)-active dye of EDP is incorporated within the biocompatible block copolymer poly­(ethylene glycol)-<i>b</i>-poly­(ε-caprolactone) for EDP NP assembly. The formulation parameters of stream velocity, dyes, and loading and concentration in FNP are optimized. The sizes of the NPs ranged from 20 to 60 nm with a ratio change of mixed solvents. As a control, an aggregation-caused quenching (ACQ) molecule of BDP was also synthesized for BDP NPs. To gain insight into the effect of the polymer on the aggregation state of hydrophobic dyes, the preparation of EDP and BDP NPs without block copolymer was also investigated. Apparently, the sizes of the NPs display large distributions without an amphiphilic block copolymer as the engineering template, suggesting that the block of polymers plays a key role in tuning the aggregation state of encapsulated dyes in FNP processes. Moreover, the peak shifts of dye with different microenvironments also confirmed the successful encapsulation of fluorescent dye in the NP cores. Finally, by externally applied forces in the FNP method, the engineered assembly of AIE-active fluorescent NPs possessing a narrow size distribution with desirable fluorescence properties was obtained. These features provide the possibility of rapidly constructing controllable AIE-active fluorescent NPs as biomedical tracers
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