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Building the UNESCO World Cultural Heritage site of Liangzhu City and its hinterlands was an enormous undertaking that required an unprecedented level of architectural innovations, clever logistic planning, and sophisticated labour organisation. We draw on environmental, archaeological and experimental data on the preparation and construction of grass-wrapped clay blocks at the Liangzhu City and investigate the importance of technological innovations to understand architectural energetics and labour organisation behind the unprecedented urbanisation at Liangzhu and beyond in prehistoric Yangtze Delta region. We estimate that each clay block took only around 5 min to prepare by 2–4 workers. Considering digging and other tasks, a small group of 3–4 workers would have been the most efficient arrangement in the preparation of grass-wrapped clay blocks. We reproduced different types of clay blocks, classified their sizes, and identified the standard sized (45x15 × 15cm) clay blocks that match with archaeological finds. Our results also show that standard-sized clay blocks had a more optimal grass-earth ratio which increased the drainage efficiency of the built clay-blocked structures and their resistance to weathering in wet conditions. The different architectural technologies applied by the Liangzhu builders constituted the Liangzhu builders' earth-building toolkit. To maximize the efficiency, labour was divided and organised according to different construction tasks. The clay-blocked structures and stone beddings were mostly built by smaller groups, who were responsible for the preparation, transportation and construction tasks. Mobilization and division of labour during these construction activities might not follow the classical top-down process. Instead, the need to apply different architectural technologies, each restrained by availability of resources, convenience of transportation, and/or intrinsic engineering properties, at construction sites in a predominantly aquatic environment, prompted a creative form of labour organisation. Our study therefore provides fresh insights into understanding labour organisation, social structure and power relations at the Liangzhu Civilisation. • Synthesis of archaeological, civil-engineering, and experimental data of earthen construction. • A creative form of labour organisation at Liangzhu emphasizing efficiency and flexibility. • Proposal of small working groups and individual construction units in earthen construction. [ABSTRACT FROM AUTHOR]

316L stainless steel is widely used for fashion jewelry, but it can carry a large number of bacteria and bring the risk of infection since the steel has no antimicrobial performance. In this paper, the effects of Ce on the antibacterial property, corrosion resistance and processability of 316L were studied by microscopic observation, thinfilm adhering quantitative bacteriostasis, and electrochemical and mechanical tests. The results show that a trace of Ce can distribute uniformly in the matrix of 316L and slightly improve its corrosion resistance in artificial sweat. With an increase in Ce content, the Ce is prone to form clustering, which degrades the corrosion resistance and the processability. The Ce-containing 316L exhibits Hormesis effect against S. aureus. A small Ce addition stimulates the growth of S. aureus. As the Ce content increases, the modified 316L exhibits an improved antibacterial efficacy. The more Ce is added, the better antibacterial capability is achieved. Overall, if the 316L is modified with Ce alone, it is difficult to obtain the optimal combination of corrosion resistance, antibacterial performance and processability. In spite of that, 0.15 wt.%-0.20 wt.% Ce around is inferred to be the best trade-off. [ABSTRACT FROM AUTHOR]

A novel near-infrared (NIR) phosphor Ca 2 MNbO 6 : Cr3+ (CMN: Cr3+, M = Ga, Al) was successfully prepared by solid-state synthesis using Li 2 CO 3 or LiF as the flux. The crystal structure of CMN: Cr3+ was characterized by the powder X-ray diffraction and refined with Rietveld methods, while the crystal structure of Ca 2 GaNbO 6 (CGN) compound were reported for the first time. Diffuse reflection, excitation, emission, lifetime, and thermoluminescence spectra were measured to investigate the optical properties of Cr3+ ions in CMN phosphors. When excited at 316 nm, Ca 2 GaNbO 6 : Cr3+ (CGN: Cr3+) exhibits a sharp R -line at 739 nm attributed to 2 E → 4 A 2 transition of Cr3+ and a broadband emission ascribed to 4 T 2 → 4 A 2 transition of Cr3+, and Ca 2 AlNbO 6 : Cr3+ (CAN: Cr3+) shows a narrow emission band centered at 745 nm corresponding to a spin-forbidden 2 E → 4 A 2 transition. The concentration quenching of Cr3+ in the CGN and CAN host was determined to be 0.4 at. % and 0.3 at. %, respectively. The critical distance of the as-prepared phosphors at the quenching concentration were calculated to be 38.06 Å for CGN: Cr3+ and 41.42 Å for CAN: Cr3+, respectively. And the energy transfer mechanism of Cr3+ in CMN: Cr3+ phosphors was certified to be the dipole - dipole interaction. The crystal field strength and the Racah parameters were calculated to evaluate the crystal-field environment of Cr3+ in the host lattices. With increasing Cr3+ ion concentration in the range of 0.1–1.0 at. %, lifetimes of the phosphors decrease from 315 μs to 211 μs (λ ex = 316 nm, λ em = 739 nm) and from 256 μs to 150 μs (λ ex = 316 nm, λ em = 756 nm) for CGN: Cr3+ and 3.70 ms–1.43 ms for CAN: Cr3+, respectively. The fluorescence decay curves of CMN: Cr3+ phosphors were fitted based on Inokuti - Hirayama model, and the parameters such as energy transfer parameter Q and energy transfer probability (P SA) were calculated. Based on the thermoluminescence (TL) glow curves of the CAN: Cr3+ phosphors, the kinetic parameters have been determined by using Chen's glow peak shape method and then the results are discussed in detail. The results show that Ca 2 MNbO 6 : Cr3+ (CMN: Cr3+, M = Ga, Al) is a new potential near-infrared phosphor for biological imaging due to its 660–840 nm emission regions. • Ca 2 MNbO 6 : Cr3+ (CMN: Cr3+, M = Ga, Al) has been synthesized by flux-assisted solid-state reaction method. • The crystal structure of CMN: Cr3+ was refined with Rietveld methods. • Photoluminescence and thermoluminescence properties of Cr3+ ions in CMN phosphors were investigated. • The fluorescence mechanism and relationship between crystal structure and optical properties of CMN: Cr3+ are analyzed. [ABSTRACT FROM AUTHOR]

Ag and its alloys, when prepared by a selective laser melting (SLM) process, have a low density and poor overall performance due to their high reflectivity when the most commonly used laser (λ = 1060 nm) is used, and they have exorbitant thermal conductivity. These characteristics lead to the insufficient melting of the powders and severely limit the applications of additive manufactured silver alloys. To improve the absorption of the laser, as well as for better mechanical properties and higher resistance to sulfidation, Ag–Cu alloys with different La2O3 contents were prepared in this work using the SLM process, via the mechanical mixing of La2O3 nanoparticles with Ag–Cu alloy powders. A series of analyses and tests were conducted to study the effects of La2O3 in Ag–Cu alloys on their density, microstructure, mechanical properties, and corrosion resistance. The results revealed that the addition of La2O3 particles to Ag–Cu alloy powders improved the laser absorptivity and reduced defects during the SLM process, leading to a significant rise from 7.76 g/cm3 to 9.16 g/cm3 in the density of the Ag–Cu alloys. The phase composition of the Ag–Cu alloys prepared by SLM was Silver-3C. La2O3 addition had no influence on the phase composition, but refined the grains of the Ag–Cu alloys by inhibiting the growth of columnar grains during the SLM process. No remarkable preferred orientation existed in all the samples prepared with or without La2O3. An upwards trend was achieved in the hardness of the Ag–Cu alloy by increasing the contents of La2O3 from 0 to 1.2%, and the average hardness was enhanced significantly, from 0.97 GPa to 2.88 GPa when the alloy contained 1.2% La2O3 due to the reduced pore defects and the refined grains resulting from the effects of the La2O3. EIS and PD tests of the samples in 1% Na2S solution proved that La2O3 addition improved the corrosion resistance of the Ag–Cu alloys practically and efficaciously. The samples containing La2O3 exhibited higher impedance values and lower corrosion current densities. [ABSTRACT FROM AUTHOR]

Single crystals of Ho3+-doped bismuth silicate (BSO) were grown by a modified Bridgman method. The spectroscopic properties for 2 μm laser operation via the 5I7 → 5I8 transition were investigated based on the absorption, emission and gain cross-section spectra of the as-grown crystal. Judd–Ofelt (J–O) theory was applied to calculate the J–O intensity parameters Ω2,4,6, spontaneous emission probabilities, branching ratios and radiative lifetimes. The Ho3+:BSO crystal was in-band pumped at 1940.3 nm by a Tm fiber laser to produce an efficient continuous wave (CW) laser output at 2109.8 nm. The maximum output power obtained was 0.73 W, and the corresponding slope efficiency with respect to the absorbed power was 38.8% and the beam propagation factor M2 of the Ho3+:BSO laser in horizontal and vertical directions was estimated to be 1.09 and 1.06, respectively. [ABSTRACT FROM AUTHOR]

This study investigated the unconfined compressive strength change law of cement modified slurries (CMS) under different curing ages. We conducted unconfined compressive strength tests using slurry and cement as raw materials. The cement contents were 5%, 10%, 15%, 20%, and 25%. The curing ages were 7, 14, 28, 56, 90, 120, 150, and 180 d. A time effect model of CMS strength was established based on the measured UCS strength-curing age and the strength-cement content curves. The test results proved that the UCS of the CMS increased significantly with an increase in the curing age, and after 90 days, the UCS gradually increased to a fixed value. The time effect model better characterized the relationship between the UCS of the CMS and the curing age and the cement content, as the predicted value had a high correlation with the measured value. We conducted scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and X-ray diffraction (XRD) tests to analyze the microstructure and chemical composition of the CMS. The microscopic test results demonstrated that the increase of cement content and curing age increased the amount of gelling substances in the CMS and made the overall structure more compact, thereby increasing its macro strength. [ABSTRACT FROM AUTHOR]

To investigate the soil structure and mechanical behavior of an unsaturated expansive clay soil, triaxial and mercury intrusion tests have been performed and are presented in this paper. Also an optical test system was developed for studying the internal structure evolution of the unsaturated expansive soil during shear-loading tests. The research results show a linear relationship between the cohesion intercept and the degree of saturation of the unsaturated clay for the test data. For the tested soil, the pore-size distribution curves were found to be bimodal. The measurement results from mercury intrusion tests confirm that the micropores of Guangxi expansive soils of this study remain constant, and that the macropores vary with the dry density of soil samples. Comparing the volumetric strain curves with the soil particle area curves, some correlation and dependence on the macropore variation of soil samples during shear-loading tests can be shown to exist. [ABSTRACT FROM AUTHOR]