Analysis On Ecological Characteristics of Mississippian Coral Reefs in Langping, Guangxi

Several Late Viséan-Serpukhovian coral reefs were identified in Langping, Tianlin. To further understand of environment that was suitable for the development of reef-building communities and the construction of coral reefs in Langping, in this paper, part of the reef-building environmental and the ecological characteristics of coral reefs then were recovered by analyzing the development settings, palaeogeography, sedimentation of reefs, the response to hydrodynamic conditions of reef-building corals, effects of disturbance and non-reef-building organism on reef communities, and the influence of coral morphology on reef development. The sedimentary environment of Langping in Late Viséan-Serpukhovian is considered to be suitable for the development of benthic communities. The current appearance of reefs is determined by both coral populations ecological characteristics and reef-building environment.

Coral-inspired hierarchical structures for sunlight harvesting

Concentrating solar thermal (CST) is an efficient renewable energy technology with low-cost thermal energy storage. CST relies on wide-spectrum solar thermal absorbers that must withstand high temperatures (> 700°C) for many years, but state-of-the-art coatings have poor optical stability. Here, we show that the largely overlooked macro-scale morphology is key to enhancing both optical resilience and light trapping. Inspired by stony-coral morphology, we developed a hierarchical coating with three tuneable length-scale morphologies: nano- (~ 120 nm), micro- (~ 3 µm) and macro-scales (> 50 µm). Our coating exhibits outstanding, stable solar-weighted absorptance of > 97.75 ± 0.04% after ageing at 850°C for more than 2,000 hours. The scalability of our coating is demonstrated on a commercial solar thermal receiver, paving the way for more reliable high-performance solar thermal systems. Scleractinia, commonly known as stony corals (Fig. 1a), have evolved their morphology over millions of years to improve their chances of survival. A symbiotic relationship with algae, which need sunlight for photosynthesis, was an evolutionary milestone 240 million years ago that enabled corals to secure nutrients in otherwise infertile waters1 and thrive in all Earth’s oceans. Sunlight attenuation in seawater initially restricted coral colonies to shallow waters2,3. To thrive in deeper waters where light is more scarce, coral morphology4 has evolved to improve light trapping5 via multiple internal light reflections (Fig. 1b, c). We can then learn from stony-coral morphology in engineering and science where light trapping is needed, including sunlight harvesting using concentrating solar thermal (CST) systems6,7. Absorber coatings applied to solar receivers in CST plants have the function of converting concentrated sunlight in a wide-spectrum into thermal energy8 for many applications, including electric power generation (Fig. 1d) 9,10. Importantly, CST incorporates thermal energy storage, a more affordable, scalable, and durable alternative than other well-known storage technologies for long duration energy storage11. A key barrier to the wide adoption of CST, contributing to both increasing cost and reducing performance, is the poor durability of its light-absorbing coatings12. These coatings need to withstand high temperatures (> 700°C) and thousands of thermal cycles over many years of operation13. The best-known CST coatings are spinel-based coatings (Supplementary Note 1) such as Pyromark 2500® (henceforth referred to as Pyromark)14, which is widely considered the gold-standard in the CST industry. These coatings implement an organic binder15 that decomposes during a curing process to produce a nano-textured porous coating with spinel pigments, without macro-scale (> 50 µm) features. Solar-weighted absorptance, the key performance metric16, is typically reported after long-term isothermal exposure at high temperature, with the highest reported values being 94.6% after ageing for 2350 h at 850°C14, 97.2% after aging for 2,000 h at 800°C15, and 96.3% after aging for 3800 h at 770°C13. However, unstable optical performance is generally observed in CST coatings because the elevated temperatures re-arrange the material phases, alter the material composition13, and modify the nano-scale morphology via sintering and crystal grain growth17. Advanced light absorbers made of carbon nanotubes18 and graphene19 can absorb more than 99% of incoming light from every angle, but these coatings burn at the surface temperatures commonly found in conventional receivers20. Most coating research so far has focused on texturing the nano-scale morphology and improving the thermal stability of the materials13,15,21−23, while neglecting the micro- (~ 3 µm) and macro-scale (> 50 µm) geometries24 and the tuning of various length-scale morphologies in the coating to maximise light absorptance. Hierarchical structures have been shown to be a powerful tool to improve radiative cooling in clothing25, as well as mechanical rigidity and stability in sea sponges26. Here, we show that a hierarchical design with coral-inspired micro- and macro-scale features can produce high-temperature solar absorbers with enhanced light absorption and outstanding optical resilience, which we define as the capacity to retain stable optical properties despite material degradation.

Improved Thermochemical Energy Storage Behavior of Manganese Oxide by Molybdenum Doping

To improve the thermochemical energy storage (TCS) behavior of Mn2O3, several Mn–Mo oxides with varying amounts of MoO3 (0–30 wt%) were prepared by a precipitation method. The physico-chemical properties of the solids were studied by N2 adsorption–desorption, X-ray diffraction (XRD), scanning electron microscopy (SEM), and H2-temperature-programmed reduction (TPR), while their TCS behavior was determined by thermogravimetric analysis coupled with differential scanning calorimetry (TGA-DSC). Apart from Mn2O3 and MoO3 phases, XRD revealed a mixed MnMoO4 phase for MoO3 loadings equal or higher than 1.5 wt%. All samples showed a well-formed coral-like surface morphology, particularly those solids with low MoO3 contents. This coral morphology was progressively decorated with compact and Mo-enriched MnMoO4 particles as the MoO3 content increased. TPR revealed that the redox behavior of Mn2O3 was significantly altered upon addition of Mo. The TCS behavior of Mn2O3 (mostly oxidation kinetics and redox cyclability) was enhanced by addition of low amounts of Mo (0.6 and 1.5% MoO3) without significantly increasing the reduction temperature of the solids. The coral morphology (which facilitated oxygen diffusion) and a smoother transition from the reduced to oxidized phase were suggested to be responsible for this improved TCS behavior. The samples containing 0.6 and 1.5 wt% of MoO3 showed outstanding cyclability after 45 consecutive reduction–oxidation cycles at high temperatures (600–1000 °C). These materials could potentially reach absorption efficiencies higher than 90% at concentration capacity values typical of concentrated solar power plants.

Class Conservation Morfologi Karang berdasarkan Kedalaman pada Struktur Terumbu Karang di Pulau Kemujan dan Pulau Sintok, Karimunjawa, Jawa Tengah Coral Morphology Class Conservation Based on Depth of Coral Reef Structure in Kemujan and Sintok Islands, Karimunjawa, Central Java

ABSTRAKKemujan dan Sintok merupakan pulau yang termasuk ke dalam zona pemanfaatan sebagai wisata bahari dan memiliki keanekaragaman bentuk pertumbuhan karang yang tinggi. Bentuk pertumbuhan karang dibedakan menjadi karang acropora dan non-acopora dengan perbedaan morfologi seperti tipe branching, massive, encruisting, foliose, dan digitae. Analisis morfologi karang sebagai pendukung status penutupan karang dapat mengetahui kondisi terumbu karang sesuai class conservation. Tujuan penelitian ini mengetahui kualitas perairan, struktur terumbu karang, morfologi karang berdasarkan class conservation dan pengaruh kedalaman terhadap struktur serta morfologi karang di Pulau Kemujan dan Sintok. Pengambilan data dilaksanakan pada bulan November 2019. Metode penelitian yang digunakan adalah metode Underwater Photo Transect (UPT) dengan menggunakan transek sepanjang 30 meter. Data yang diambil adalah parameter kualitas perairan dan foto underwater karang. Data hasil penelitian diolah menggunakan aplikasi CPCe (Coral Point Count with Excel extensions) dan uji non parametrik dengan SPSS serta dianalisis menggunakan diagram r-K-S. Hasil penelitian menunjukkan bahwa kualitas perairan pada lokasi penelitian masih dalam keadaan normal. Persentase kelimpahan karang hidup termasuk dalam kategori sedang sampai dengan sangat baik yaitu berkisar 25,56 -76,22%. Persentase morfologi karang berdasarkan Class conservation secara umum memiliki dominasi kelompok kompetitors (K) atau CC=2 yang berkisar 48,72 – 76,5%, hal ini menunjukkan bahwa pada lokasi penelitian didominasi karang bentuk branching maupun foliose serta tidak ada pengaruh signifikan kedalaman air terhadap morfologi karang. ABSTRACTKemujan and Sintok are islands in the utilization zone as marine tourism and have high diversity of coral growth forms. The coral’s life form can be grouped into acropora and non-acopora corals with morphological differences such as branching, massive, encruisting, foliose, and digitae types. Morphological analysis of corals as supporting the status of coral cover can determine the condition of coral reefs according to class conservation. The purpose of this study are to determine the quality of the waters, the structure of coral reefs, coral morphology based on class conservation and the influence of depth on the structure and morphology of corals in Kemujan and Sintok Islands. Data collection was carried out in November 2019. The research method used was the Underwater Photo Transect (UPT) method using a 30 meter transect. The data collected the parameters of water quality and underwater coral photos. The research data were processed using the CPCe (Coral Point Count with Excel extensions) application and non-parametric tests with SPSS and analyzed using the r-K-S diagram. The results showed that the water quality at the study area was still in a normal condition. However, there was no significant effect of water depth on coral morphology. The percentage of live coral abundance was included in the moderate to very good category, ranging from 25.56 to 76.22%. Percentage of coral morphology based on Class conservation generally has a predominance of competitor groups (K) or CC = 2 ranging from 48.72 - 76.5%. Moreover, the results show that based on the coral growth forms at the study sites were dominated by branching and foliose corals and there was no significant effect of water depth on coral morphology.

Comparison of 3D Coral Photogrammetry and Coral Video Transect for Coral Lifeform Analysis Using Low-cost Underwater Action Camera

This research analysed the use of 3D Coral Photogrammetry (CP) and Coral Video Transect (CVT) images collected from SCUBA divers using a low-cost underwater action camera to examine the coral lifeform. A comparison was made between data sets obtained using both methods on nine transects with different coral lifeform compositions and percentage cover within an area of 4 × 7 m. The comparison of the statistical analysis for CPCe revealed that there were no significant differences (p < 0.05) between CP and CVT photos where dead corals (p = 0.006), sand (p = 0.011), and unknown (p = 0.002) are present. Additionally, the coral value (p = 0.131) between CP and CVT was not significant. CP was capable of producing prominent branching, massive, and plate coral morphology results. This suggests that survey methods using low-cost action cameras for 3D Coral Photogrammetry would yield appropriate results in terms of coral lifeform detection. Hypothetically, by improving camera quality, it will yield a higher accuracy of 3D coral images that are suitable for use in scientific research and management. Other benefits of using CP include the possibilities for future studies with 3D coral surveys using remotely operated vehicles, less field time, and 3D coral seabed information.

Nanostructured zeolite with brain-coral morphology and tailored acidity: a self-organized hierarchical porous material with MFI topology

Nano-zeolite with brain-coral morphology formed by self-organization of ultra-small nanospheres, exhibits micro/meso porosity with high surface area, distributed acid sites, and reduced diffusion resistance making it a promising solid acid catalyst.