•The application study of thixotropic nano clay on novel 3D printing concrete ink.•The buildability and rheology property of novel 3D printing concrete ink.•The thixotropy model of novel 3D printing ...concrete ink is provided.•The relationship between structure re-build and hydration heat is presented.
3D printing technique is an opportunity for the development of architecture industry altered by the emergence of 3D printing concrete ink that shows unconventional characteristics mainly originated from its geometric design. In this paper, a novel 3D printing concrete ink that has good fluidity during movement and satisfying standing behavior at static state due to the structural rebuilding of cement paste advanced by the addition of nano clay (NC) and silica fume (SF) was specially designed to be extruded through a nozzle to print layer-over-layer components for an innovative additive manufacturing process. The buildability, rheological properties (viscosity, yield stress and thixotropy), workability, green strength, open time and hydration heat of the fresh 3D printing concrete were systematically investigated. Results indicated that the buildability of this concrete with a small quantity of NC or SF were increased by 150% and 117%, respectively, and remarkably enhances the thixotropy and green strength. The double-doped NC and SF optimize the buildability.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
•Extrudability of printing geopolymer was evaluated by structure rebuilding ability.•Buildability of printing geopolymer linked to the development of yield stress.•Lower Si/Na ratio useful improve ...the workability of printing geopolymer.
For 3D printing construction materials, workability and interlayer force of fresh printing pastes were necessary to ensured extrudability and buildability in the period from extrude to hardened of pastes. The workability and interlayer force of 3 Dimensional printing geopolymer pastes related to its rheological property and more particularly to its structure rebuilding and yield stress. The present study is aimed at investigating structure rebuilding and yield stress of 3 Dimensional printing geopolymer pastes at different Si/Na ratio of alkali activator by rheology method. Results revealed that rheology is an important research method for the extrudability and buildability of 3D printing geopolymer pastes. Structure rebuilding ability (SRE) and fast-growing yield stress of 3 Dimensional printing geopolymer ensured the stability of structure in the period from extrude to hardened of paste. Si/Na ratio of alkali activator has significantly influences on extrudability and buildability of 3D printing geopolymer pastes. High Si/Na ratio of alkali activator decreases the viscosity, yield stress and development rate of fresh pastes. Si/Na ratio of alkali activation significantly influences rate of structure rebuilding of pastes, and low Si/Na ratio of alkali activator exhibited high ability of recovery of pastes.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Der Aufsatz untersucht anhand des hessischen Kultusministeriums, wie in der unmittelbaren Nachkriegszeit (ca. 1946–1951) versucht wurde, durch Lehrerbildung neue demokratische Werte zu etablieren und ...zu vermitteln. Hierzu verfolgt er die Bemühungen der Psychologin Brigitte Schliebe-Lippert (1898–1993), die von 1946 bis zu ihrer Pensionierung im Jahr 1963 das Referat Lehrerbildung im hessischen Kultusministerium leitete. Schliebe-Lippert ist einerseits als Frau in einer ministerialen Leitungsposition eine Ausnahmeerscheinung. Andererseits ist sie als in Gießen im Jahr 1932 habilitierte Psychologin Teil einer frühen und kleinen Gruppe von habilitierten Frauen. Sie vertrat in der Nachkriegszeit die These, dass die Bemühungen um Reeducation seitens der amerikanischen Militärregierung vor allem auf der Basis einer wissenschaftlichen Psychologie zu unterstützen seien. Vorliegender Aufsatz fragt danach, in welchem Modus der Zusammenarbeit mit den amerikanischen Militärbehörden Schliebe-Lippert versuchte, ihre Version der Entwicklungspsychologie zu platzieren. Es wird überdies untersucht, inwiefern Wissenschaftlichkeit im Allgemeinen und sozial- und humanwissenschaftliche Wissenschaften wie die Psychologie im Besonderen in den Augen der Akteur:innen Grundlagen waren, auf denen neue demokratische Werte begründet werden konnten. Dabei werden die Positionen Schliebe-Lipperts im Kontext der deutschen Diskussionen über Lehrerbildung und vor dem Hintergrund ihrer Aktivitäten während des Nationalsozialismus kontextualisiert. Der Beitrag stützt sich auf den Nachlass Schliebe-Lipperts und Überlieferung zur Lehrerbildung im Hessischen Hauptstaatsarchiv, weitere Archivquellen in Frankfurt und Mainz sowie publizierte Texte.
This paper critiques the traditional project management (PM) approach for post-disaster reconstruction work in relation to long-term effectiveness at strengthening disaster resilience of communities. ...While assessments of post-disaster reconstruction projects normally occurs within a few years of the disaster this paper is based on a study of four ‘good practice’ reconstruction projects, 15years after the earthquake and seven years after the flooding disaster from the Indian states of Gujarat and Bihar respectively. This extended timeframe enabled the examination of long-term outcomes related to disaster resilience of communities. The comparison of the four case study projects through extended timeframe enabled authors to articulate critical success factors contributing to project's effectiveness. The research found that the best long-term outcomes were achieved when the agencies implementing post-disaster housing reconstruction projects: 1) adopted an ‘agile’ approach to project planning and implementation; 2) allocated ample time for gaining and maintaining community trust; iii) provided multiple materials, technologies and skilled labour choices to ensure hazard-safety of housing, and (iv) continued community capacity building beyond the completion of the reconstruction work. These imperatives have prompted the development of a progressive, spiral model for effective post-disaster housing reconstruction project management which is presented in this paper.
Empirical research paper.
•A traditional project management inadequate for post-disaster reconstruction (PDR).•PDR allows for rebuilding safer houses and enhancing resident's disaster resilience.•Research on the long term effectiveness of PDR projects for disaster resilience.•A new model for effective PDR project management is developed based on findings.•The new model has an agile, contextual, socio-technical and time flexible approach.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The alpine meadow ecosystem on the Qinghai-Tibet Plateau has degenerated greatly in recent decades. The most effective means of restoration for severely degraded grasslands is rebuilding artificial ...grasslands. However, the effects of converting severely degraded grasslands to artificial grasslands on soil respiration and the relationships between soil respiration and carbon and nitrogen storage remain unclear. Therefore, we evaluated soil respiration and carbon and nitrogen storage on native grasslands with different levels of degradation (no degradation (ND), lightly degraded (LD), moderately degraded (MD) and severely degraded (SD)); the study was on a perennial artificial grassland with different restoration years (cultivated for 3 years (A3) and cultivated for 16 years (A16)) and on an annual oat grassland in an alpine meadow of the Qinghai-Tibet Plateau and applied a structural equation model to explore the relative contributions of biotic and abiotic variables in the regulation of soil respiration. Our results demonstrated that grassland degradation significantly decreased the growing season soil respiration, annual mean soil respiration, vegetation, and the soil and ecosystem carbon and nitrogen storage. Meanwhile, the establishment of annual oat grasslands significantly decreased the growing season soil respiration, annual mean soil respiration, 0–30cm soil layer and ecosystem carbon and nitrogen storage, whereas it significantly increased the vegetation carbon and nitrogen storage. In contrast, the perennial artificial grassland had no significant effect on the growing season soil respiration or on the annual mean soil respiration but significantly increased the forage yield and ecosystem carbon and nitrogen storage. Grassland degradation and artificial grassland establishment had no significant effect on the dormant season soil respiration. Furthermore, soil moisture had a greater impact on growing season soil respiration, whereas soil temperature had a more significant effect on the dormant season soil respiration. Furthermore, a structural equation model indicated that the carbon storage in the roots and the 0–10cm soil layer were two important biotic factors that controlled soil respiration. Considering the ecological and productive properties, establishing a perennial artificial grassland could be the best strategy for restoring the black-soil-type grasslands native to the Qinghai-Tibet Plateau.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
This paper examines the long-run causal effects of management on firm performance. Under the United States Technical Assistance and Productivity Program (1952–1958), the United States organized ...management training trips for Italian managers to US firms and granted technologically advanced machines to Italian companies. I exploit an unexpected budget cut that reduced the number of participating firms and find that, compared to businesses excluded by the budget cut: performance of Italian firms that sent their managers to the United States increased for at least fifteen years after the program; performance of companies that received new machines increased, but flattened out over time; management and new machines were complementary.
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BFBNIB, CEKLJ, INZLJ, IZUM, KILJ, NMLJ, NUK, ODKLJ, PILJ, PNG, SAZU, UL, UM, UPUK, ZRSKP
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•NiAl layered double oxides were synthesized.•NiAl layered double oxides have large adsorption capacities for As(V) ions.•The removal mechanisms of As(V) on NiAl layered double oxides ...are surface adsorption and intercalation reconstruction.
The NiAl layered double hydroxides (NiAl-LDHs) as well as NiAl layered double oxides (NiAl-LDOT, T: 300, 400, 500, 600 °C) were successfully synthesized by hydrothermal process and calcination treatment, and served as adsorbents for the efficient uptake of arsenate (As(V)) from aqueous solutions. Batch experiments were carried out at various solution pH, original As(V) concentration, contact time and calcination temperature. It was found that As(V) adsorption capacity on these composites can be changed by controlling the calcination temperature, and followed the order NiAl-LDO500 (198.1 mg/g) > NiAl-LDO400 (180.9 mg/g) > NiAl-LDO300 (160.2 mg/g) > NiAl-LDO600 (121.4 mg/g) > NiAl-LDH (60.7 mg/g), which could be ascribed to abundant surface adsorption sites and a “memory effect” provided by “Ni-O or Al-O” bonds. The thermodynamic experiments revealed that the elimination of As(V) was spontaneous and endothermic. In addition, multiple characterizations and batch experiments have been carried out to prove the surface adsorption and intercalation by rebuilding of primary layered structure contributed to As(V) adsorption. This discovery can provide a new insight into the elimination of As(V) from wastewater for environmental remediation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The metal sulfide or selenides have attracted increasing attention for high‐energy lithium‐ion batteries due to their unique layer structure flexibility, higher conductivity, and lower voltage ...polarization than metal oxides. However, low initial coulomb efficiency (ICE), serious structure destruction, and irreversible bonding chemistry are still big challenges for their practical application. Herein, layer GeSe2 and its carbon composite are synthesized by high‐energy ball milling and it is surprisingly found that crystalline c‐GeSe2 possesses higher reversible capacity and better rate performances than their amorphous counterparts. More specially, the broken GeSe bondings upon lithiation are also observed to regenerate after delithiation. These unusual phenomena are investigated by both experimental tools and theoretical calculations. Compared to other typical MX2 (M = Mo, W, X = S, Se), the electronegativity of Ge is more close to selenium and the formation energy of GeSe bonding is much smaller. Thus, a mild driven force such as thermoheating at low temperature can recover the ordered layer structure, helping to heal the high conductivity and unimpeded Li diffusion pathways for crystalline GeSe2. Similarly, electrochemical delithium force also triggers the rebuilding of GeSe bonding upon Li‐extraction, boosting GeSe2/C with large capacity (1050 mA h g−1), ultrahigh ICE (94%), and cycling stability.
Due to the low formation energy of GeSe bondings, a mild driven force such as thermoheating can recover the ordered layer structure, helping c‐GeSe2 to get better rate performances than its amorphous counterparts. Electrochemical delithium force also triggers the rebuilding of GeSe bonding upon Li‐extraction, boosting GeSe2/C with large capacity (1050 mA h g−1), ultrahigh initial coulomb efficiency (94%), and cyclability.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
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