| 1. |
- Woo, Jong Hun, et al.
(författare)
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Assessment Framework of Smart Shipyard Maturity Level via Data Envelopment Analysis
- 2021
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Ingår i: Sustainability. - : MDPI AG. - 2071-1050. ; 13:4
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Tidskriftsartikel (refereegranskat)abstract
- The fourth industrial revolution ("Industry 4.0") has caused an escalating need for smart technologies in manufacturing industries. Companies are examining various cutting-edge technologies to realize smart manufacturing and construct smart factories and are devoting efforts to improve their maturity level. However, productivity improvement is rarely achieved because of the large variety of new technologies and their wide range of applications; thus, elaborately setting improvement goals and plans are seldom accomplished. Fortunately, many researchers have presented guidelines for diagnosing the smartness maturity level and systematic directions to improve it, for the eventual improvement of productivity. However, most research has focused on mass production industries wherein the overall smartness maturity level is already high (e.g., high-level automation). These studies thus have limited applicability to the shipbuilding industry, which is basically a built-to-order industry. In this study, through a technical demand survey of the shipbuilding industry and an investigation of existing smart manufacturing and smart factories, the keywords of connectivity, automation, and intelligence were derived and based on these keywords, we developed a new diagnostic framework for smart shipyard maturity level assessment. The framework was applied to eight shipyards in South Korea to diagnose their smartness maturity level, and a data envelopment analysis (DEA) was performed to confirm the usefulness of the diagnosis results. By comparing the DEA models, the results with the smart level as an input represents the actual efficiency of shipyards better than the results of conventional models.
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| 2. |
- Zhou, Yongqiang, et al.
(författare)
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Rainstorm events shift the molecular composition and export of dissolved organic matter in a large drinking water reservoir in China : High frequency buoys and field observations
- 2020
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Ingår i: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 187
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Tidskriftsartikel (refereegranskat)abstract
- Rainstorm events can flush large amounts of terrestrial organic-rich material into lakes that are used for drinking water. To date, few studies have been carried out to investigate how rainstorm events change the molecular composition, bio-lability, and flux of upstream-imported dissolved organic matter (DOM), which can impact the odor and taste of drinking water as well as the efficiency of wastewater treatment. We undertook high-frequency buoy monitoring and point sample collection (n = 495), during high, moderate, and low inflow discharge, in Lake Qiandao, a key drinking water source for about 10 million people. Data from two online fluorescent DOM sensors deployed and field samples collected at the river site, Jiekou, and the lake site, Xiaojinshan, showed that rainstorm events increased the specific UV absorbance (SUVA254), humification index (HIX), humic-like components (C1-C2), and FT-ICR MS derived condensed aromatic and polyphenolic compounds (p < 0.001) and decreased the spectral slope of DOM (S275–295), spectral slope ratio (SR), biological index (BIX), and highly bio-degradable peptide-like and aliphatic substances (p < 0.001). Our results suggest that rainstorm events enhanced the export to the lake of colored, hydrophobic, and aromatic DOM. Upstream-derived dissolved organic carbon (DOC) concentrations decreased (p < 0.001), while DOC bio-availability (BDOC) increased only slightly (p < 0.05) during rainstorm events. The loss rate of DOC in Lake Qiandao is 0.82 × 104 t C yr−1, of which 0.30 × 104 t C yr−1 is highly bio-labile, and higher occurrences of both ≥ 25 mm d − 1 and ≥ 50 mm d − 1 rainfall events are anticipated by linear fittings for this region in the future. The application of in situ fluorescence sensors provides an early warning of DOC surge incidents caused by rainstorm events and may be useful in advising drinking water treatment plant managers of changes in raw water DOM quality and treatability.
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| 3. |
- Zhu, Jie, et al.
(författare)
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Highly secretory expression of recombinant cowpea chlorotic mottle virus capsid proteins in Pichia pastoris and in-vitro encapsulation of ruthenium nanoparticles for catalysis
- 2020
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Ingår i: Protein Expression and Purification. - : Elsevier BV. - 1046-5928 .- 1096-0279. ; 174
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Tidskriftsartikel (refereegranskat)abstract
- The applications of viral protein cages have expanded rapidly into the fields of bionanotechnology and materials science. However, the low-cost production of viral capsid proteins (CPs) on a large scale is always a challenge. Herein, we develop a highly efficient expression system by constructing recombinant Pichia pastoris cells as a “factory” for the secretion of soluble cowpea chlorotic mottle virus (CCMV) CPs. Under optimal induction conditions (0.9 mg/mL of methanol concentration at 30 °C for 96 h), a high yield of approximately 95 mg/L of CCMV CPs was harvested from the fermentation supernatant with CPs purity >90%, which has significantly simplified the rest of the purification process. The resultant CPs are employed to encapsulate Ruthenium (Ru) nanoparticles (NPs) via in-vitro self-assembly to prepare hybrid nanocatalyst, i.e. Ru@virus-like particles (VLPs). The catalytic activity over Ru@VLPs was evaluated by reducing 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). The results indicate that, with the protection of protein cages, Ru NPs were highly stabilized during the catalytic reaction. This results in enhanced catalytic activity (reaction rate constant k = 0.14 min−1) in comparison with unsupported citrate-stabilized Ru NPs (Ru-CA) (k = 0.08 min−1). Additionally, comparatively lower activation energy over Ru@VLPs (approximately 32 kJ/mol) than that over Ru-CA (approximately 39 kJ/mol) could be attributed to the synergistic effect between Ru NPs and some functional groups such as amino groups (–NH2) on CPs that weakened the activation barrier of 4-NP reduction. Therefore, enhanced activity and decreased activation energy over Ru@VLPs demonstrated the superiority of Ru@VLPs to unsupported Ru-CA.
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| 4. |
- Zhu, Ying, et al.
(författare)
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Effects of divalent copper on tetracycline degradation and the proposed transformation pathway
- 2020
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Ingår i: Environmental Science and Pollution Research. - : Springer. - 0944-1344 .- 1614-7499. ; 27:5, s. 5155-5167
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Tidskriftsartikel (refereegranskat)abstract
- To reveal the characteristics of tetracycline (TC) photocatalytic degradation under Cu(II) coexistence, effects of Cu(II) on TC photocatalytic degradation by ZnO nanoparticles (ZnO NPs) as a function of pH, humic acid (HA), and initial Cu(II) concentration were investigated. Interaction of TC with Cu(II) in the treatment process was analyzed by circular dichroism (CD) spectroscopy, while TC degradation pathway was investigated by high-performance liquid chromatography-mass spectrometry. Sixty-five percent and ninety-one percent TC degradation within 60 min in the absence and presence of Cu(II), respectively, was reported. Both adsorption and photocatalytic degradation of TC under Cu(II) coexistence increased with increasing pH from 3 to 6, while decreased with further increase in pH. HA inhibited the degradation of TC by ZnO NPs both in the presence as well absence of Cu(II), while TC degradation decreased from 91 to 73% and from 73 to 37% in the presence and absence of Cu(II), respectively. TC degradation by ZnO NPs first increased then decreased with increasing Cu(II). Maximum TC degradation (about 94%) was obtained in the optimum concentration range of Cu(II) (0.05-0.15 mmol/L). In addition, there was a lag effect between TC adsorption and degradation on ZnO NPs. TC degradation was improved via Cu(II)-TC surface complexation and followed N-demethylation and hydroxylation routes. This study could be of potential importance in extrapolating the transformation of TC or other antibiotics under the coexistence of heavy metals in water.
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