Highlights
The (SnO
2
-cPCN) ETL shows superior electron mobility of 3.3 × 10
−3
cm
2
V
−1
s
−1
, which is about three times higher than that of pristine SnO
2
.
The less wettable SnO
2
-cPCN leads ...to perovskite layers with reduced grain boundaries and enhanced qualities due to suppressed heterogeneous nucleation of perovskite.
The PSCs based on SnO
2
-cPCN showed negligible
J
–
V
hysteresis and two champion PCE of 23.17% and 20.3% on devices with 0.1 and 1 cm
2
active area, respectively.
Efficient electron transport layers (ETLs) not only play a crucial role in promoting carrier separation and electron extraction in perovskite solar cells (PSCs) but also significantly affect the process of nucleation and growth of the perovskite layer. Herein, crystalline polymeric carbon nitrides (cPCN) are introduced to regulate the electronic properties of SnO
2
nanocrystals, resulting in cPCN-composited SnO
2
(SnO
2
-cPCN) ETLs with enhanced charge transport and perovskite layers with decreased grain boundaries. Firstly, SnO
2
-cPCN ETLs show three times higher electron mobility than pristine SnO
2
while offering better energy level alignment with the perovskite layer. The SnO
2
-cPCN ETLs with decreased wettability endow the perovskite films with higher crystallinity by retarding the crystallization rate. In the end, the power conversion efficiency (PCE) of planar PSCs can be boosted to 23.17% with negligible hysteresis and a steady-state efficiency output of 21.98%, which is one of the highest PCEs for PSCs with modified SnO
2
ETLs. SnO
2
-cPCN based devices also showed higher stability than pristine SnO
2
, maintaining 88% of the initial PCE after 2000 h of storage in the ambient environment (with controlled RH of 30% ± 5%) without encapsulation.
LaMeAl11O19 ceramics is a kind of thermal barrier coating（TBC） material with promising application prospect due to its unique crystal structure, excellent thermodynamic properties, low thermal ...conductivity, and high temperature phase stability. Here, LaMeAl11O19/YSZ（Me=Mg, Cu, Zn） thermal barrier coatings were prepared by atmospheric plasma spraying（APS）. Failure analysis of the coating was carried out by burner rig test and other analysis techniques. The results show that LaMgAl11O19（LMA）, LaZnAl11O19（LZA） and LaCuAl11O19（LCA）powders are decomposed during the plasma spraying, resulting in different contents of magnetoplumbite phase in the coatings, which may be an important factor responsible for their distinction of thermal cycling lifetimes. The LaMeAl11O19 layer is delaminated upon YSZ layer due to mismatch of thermal expansion coefficient between LaMeAl11O19 layer and YSZ layer and volume shrinkage caused by recrystallization of amorphous phase. Then the YSZ layer is exposed high temperature, accelerating sintering and TGO growth, and promoting the delamination of the YSZ layer from the bond coat. At low temperature, with the increase of the atomic number of the divalent Me2+,the thermal conductivity of the LaMeAl11O19 decreases. At high temperature, LCA coating has better infrared emissivity（0.88, 600 ℃） than both LMA and LZA, which weakens the contribution of photon conduction to thermal conductivity and leads to the reduction of thermal conductivity. Therefore, LCA coating has potential application in high temperature infrared radiation coating.
SiC-based ceramic matrix composites (SiC-CMC) are an ideal material for aeroengines with high thrust/mass ratio.In order to prevent the corrosion of SiC-CMC by gas (rich in H2O and O2) in the engine, ...it is necessary to prepare environmental barrier coatings (EBCs) with excellent water and oxygen corrosion resistance, gas erosion resistance and thermal shock resistance. Among many factors that evaluate the performance of EBCs, the bonding strength between EBCs and SiC-CMC matrix is an important indicator, but the limit value of the bonding strength has not been clearly explored.In this paper, main factors to control the bonding strength were studied in order to reach the highest value, including the SiC-CMC matrix state, the tensile strength limit of single crystal Si, and the preparation process of the Si bonding layer, etc. In the SiC-CMC/EBCs system, the interface between the SiC fiber cloth is the weakest part of the bonding strength, followed by the Si bonding layer. The bonding strength limit is 15 MPa,
La2Hf2O7 (LH) ceramics with pyrochlore structure have excellent phase stability up to 1600 °C, and far superior sintering resistance as well as comparable mechanical properties to typical 8 wt% ...yttria-stabilized zirconia (8YSZ). More importantly, they have the coefficients of thermal expansion (CTEs) of 8.76 × 10−6 K−1, lower than that of 8YSZ (10.38 × 10−6 K−1), and thermal conductivities of 1.34 W/m·K at 1000 °C, approximately 40% lower than that of 8YSZ (2.1–2.22 W/m·K). These comprehensive properties promote them as thermal insulation top-coats in thermal/environmental barrier coatings (T/EBCs) on ceramic-matrix composites (CMCs) or top-coats of double-ceramic-layered thermal barrier coatings (DCL-TBCs) on superalloys.
The accuracy of flow cytometric (FCM) quantifications of microbial populations in sediments varies with FCM settings, cell extraction and staining protocols, as well as sample types. In the present ...study, we improve the accuracy of FCM for enumerating microorganisms inhabiting diverse lake and marine sediment types based on extensive tests with FCM settings, extraction buffer chemical compositions, cell separation methods, and staining procedures. Tests on the FCM settings, (e.g., acquisition time, rates of events) and salinity of extraction solutions show minor impacts on FCM enumerations and yields of cell extraction, respectively. Existing methods involving hydrofluoric acid (HF) treatment to release sediment-attached cells into solution prove effective on both marine and freshwater samples. Yet, different staining techniques (direct staining of cell extracts, staining of membrane-filtered cell extracts) produce clear differences in cell number estimates. We demonstrate that, while labor-intensive membrane-staining generates high cell staining efficiency and accurate cell counts that are consistent across FCM and epifluorescence microscopy-based (EFM) quantification methods, accurate cell counts determined by more time- and labor-efficient direct staining require consideration of dye concentration, sample dilution, and lithology. Yet, good agreement between the two staining methods can be achieved through sample-specific adjustments of dye concentrations and sample dilutions during direct staining. We thus present a complete protocol for FCM-based cell quantification, that includes all steps from the initial sample fixation to the final enumeration, with recommendations for buffer compositions, direct and membrane-based staining procedures, and the final FCM assay. This protocol is versatile, accurate, and reliable, as is evident from good agreement with cell quantifications by EFM and quantitative polymerase chain reaction (qPCR) of 16S rRNA genes across a wide range of sedimentary sample types.
Thermal-sprayed coatings are expected to have a relatively smooth surface when used under certain service conditions, such as to improve their erosion resistance or decrease the adhesion of CMAS ...sands. In this study, a new method for grinding ceramic coatings was proposed that uses an industrial robot, a floating spindle, a rubber binder grinding head, and diamond plaster to automatically grind ceramic coatings on basis of free abrasive grinding. Typical 8YSZ thermal barrier coatings (TBCs) were created on nickel-based superalloy plates using atmospheric plasma spraying (APS) in order to explore the impact of such grinding on their morphology and comprehensive performance. Following the grinding with the proposed process, the coating's surface roughness, removal weight and thickness, as well as 3D surface morphology were all measured. The microstructure, wetting angle, infrared emittance, microhardness, bonding strength, particulate erosion resistance, and thermal cycling life of the as-sprayed and ground 8YSZ coatings were comparatively studied using the corresponding characterization instrument. The results show that the coating's surface roughness can be decreased to roughly 1 μm, and its removal thickness ranges between 45 and 90 μm. Besides from the wettability of the droplet on the coating's surface rises, the coating's infrared emittance, mechanical properties, thermal cycling life, and erosion resistance are not noticeably different after grinding, demonstrating that such novel grinding technique won't weaken the microstructure or shorten the coating life. It could offer guidance for the urgently required development of grinding processes for ceramic coatings with complex surfaces.
LaMgAl11O19（LMA） coating prepared by atmospheric plasma spraying has large amounts of amorphous phase,which seriously affects the service life of coating.Effects of microstructure,such as grain ...size,porosity and amorphous phase content,on mechanical,thermophysical and thermal shock resistance properties of LMA coatings after heat-treatement at 900–1600℃for 12 h were investigated.The results show that the as-sprayed LMA coating possesses two crystallization temperature points,900 and 1163℃.After heat-treatement at 900℃,the lowest thermal diffusivity of 0.53 mm~2/s was obtained for LMA coating at 1000℃due to the large amount of amorphous phase and the highest porosity of （18.88±2.15）%.LMA coatings,heat-treated at 1100–1400℃,exhibited higher hardness owing to reduced amorphous content and porosity through recrystallization and sintering with the maximum hardness of （12.08±0.58） GPa at 1100℃.After heat-treatement at 1300℃,the coating displayed the highest average thermal cycling life （588 times）,which was attributed to abundant micron flake crystals with high strain tolerance.When the heat-treatment temperature reached 1500℃,the grain thickness increased rapidly due to parallel stacking of lamellar crystals,porosity increased and mechanical properties significantly decreased.During the thermal shock,grain breaking and crack propagation occurred in the coating due to the repeated thermal stress,resulting in final failure of the coating.
Even though sediment macrofauna are widespread in the global seafloor, the influence of these fauna on microbial communities that drive sediment biogeochemical cycles remains poorly understood. ...According to recent field investigations, macrofaunal activities control bacterial and archaeal community structure in surface sediments, but the inferred mechanisms have not been experimentally verified. Here we use laboratory microcosms to investigate how activities of two major polychaete guilds, the lugworms, represented by
Abarenicola pacifica
, and the clamworms, represented by
Nereis vexillosa
, influence microbial communities in coastal sediments.
A. pacifica
treatments show >tenfold increases in microbial cell-specific consumption rates of oxygen and nitrate, largely due to the strong ventilation activity of
A. pacifica
. While ventilation resulted in clearly elevated percentages of nitrifying archaea (
Nitrosopumilus
spp.) in surface sediments, it only minorly affected bacterial community composition. By comparison, reworking – mainly by deposit-feeding of
A. pacifica
– had a more pronounced impact on microorganismal communities, significantly driving down abundances of Bacteria and Archaea. Within the Bacteria, lineages that have been linked to the degradation of microalgal biomass (e.g., Flavobacteriaceae and Rhodobacteraceae), were especially affected, consistent with the previously reported selective feeding of
A. pacifica
on microalgal detritus. In contrast,
N. vexillosa
, which is not a deposit feeder, did not significantly influence microbial abundances or microbial community structure. This species also only had a relatively minor impact on rates of oxygen and nitrogen cycling, presumably because porewater exchanges during burrow ventilation by this species were mainly restricted to sediments immediately surrounding the burrows. Collectively our analyses demonstrate that macrofauna with distinct bioturbation modes differ greatly in their impacts on microbial community structure and microbial metabolism in marine sediments.
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