Hydrogeochemistry and Acidic Property of Submarine Groundwater Discharge Around Two Coral Islands in the Northern South China Sea

Submarine groundwater discharge (SGD) is an important source of nutrients in many coastal regions, yet little information is available on its carbonate chemistry and controlling factors. This study examined the processes and factors controlling the hydrogeochemistry and acidic property of the groundwaters and SGD waters of two isolated coral islands, Liuqiu Island (13 km off southwestern Taiwan) and Dongsha Island (located in the northern South China Sea, 420 km away from Liuqiu Island). Our results showed that the total alkalinity and dissolved inorganic carbon (DIC) of the fresh SGD waters were controlled mainly by the chemical weathering of carbonate minerals. Part of the DIC came from the organic matter decomposition or soil CO2, reducing the pH and CO32− concentration. Distributions of the carbonate chemistry and nutrients of the SGD waters were controlled mainly by physical mixing between the groundwater and the ambient seawater under the seabed, the so-called subterranean estuary. The Ca2+ released through weathering significantly increased the saturation state of aragonite or calcite, reducing the corrosiveness of the SGD waters on the carbonate rocks. This study is likely the first to examine the effects of the acidic property of SGD waters on the biogenic carbonate spine of a sea urchin and a pteropod shell. The spring water with similar carbonate chemistry to that of the freshwater SGD endmember from Liuqiu Island with a saturation state of aragonite of 0.96 caused observable dissolution on the spine of a sea urchin and a pteropod shell, but the spine dissolved more readily. This was because the spine is made of high-Mg calcite, which has higher solubility than that of aragonite or calcite. Such a result implies that some marine organisms with carbonate skeletons or shells containing high Mg:Ca ratios may suffer the impact of ocean acidification earlier. Although the SGD may contribute less than 10% of freshwater discharge by rivers to the coastal area, its impact on coastal biogeochemical cycles and ecosystems due to its acidic property and continual effect on the coast all year round deserves further investigation.

Composite Nanostructure of Manganese Cluster and CHA-Type Silicoaluminaphosphates: Enhanced Catalytic Performance in Dimethylether to Light Olefins Conversion

Light olefins, especially ethylene and propylene, are important chemicals in petrochemical industries with an increasing demand and play an essential role in the global consumption. In this regard, there have been extensive studies to design efficient catalysts for the light olefins productions. In this study, we report a new protocol to induce Mn nanoclusters (MnNC) into the mesopore of a CHA-type silicoaluminaphosphates via a one-pot synthesis of MnNC@SAPO-34 catalysts. The catalysts are characterized by a series of technology, such as TEM, XRD, NH3-TPD, 27Al MAS NMR, ICP-MS, XPS, and as well as N2-physical adsorption methods. The Mn nanoclusters of Mn2O3 and MnO2 species are well dispersed in the framework of the SAPO-34 silicoaluminaphosphates, modifying the porosity and acidic property of the SAPO-34: Giving rise to more mesoporous and improving the acid density. The MnNC@SAPO-34 catalysts exhibit decent 100% conversion and 92.2% olefins selectivity in the dimethyl ether to olefins (DTO) reactions, which is considerably higher than that for SAPO-34 silicoaluminaphosphates (79.6% olefins selectivity). The higher olefins selectivity over the MnNC@SAPO-34 is deemed to associate with the strong acid density and intensity of the silicoaluminaphosphates. Further, the Mn particles largely improve silicoaluminaphosphates’s durability.

In silico analysis of bacterial translation factors reveal distinct translation event specific pI values

Background Protein synthesis is a cellular process that takes place through the successive translation events within the ribosome with the help of the event-specific protein factors, namely, initiation, elongation, release, and recycling factors. The translation process is fundamental to all organisms living in the wide variety of environments. In this regard, we asked the questions about how similar are those translation factors to each other from a wide variety of bacteria? Hence, we did a thorough in silico study of the translation factors from 495 bacterial sp., and 4262 amino acid sequences, wherein we theoretically measured their pI and MW values that are the two determining factors for distinguishing individual proteins in 2D gel electrophoresis. Then we analyzed the output from various angles. Results Our study revealed that, not all the pI values are same or random, but there is a distinct order, such that the pI values of translation factors are translation event specific. We found that the translation initiation factors are mainly basic, whereas, elongation and release factors that interact with the inter-subunit space of the intact 70S ribosome during translation are strictly acidic. Further analysis revealed that the acidic property of those factors is due to the higher frequencies of glutamic acids. However, two translation factors, the translation initiation factor 2 (IF2) and the ribosome recycling factor (RRF) showed variable pI values. Remarkably, the variability of the pI values of these two factors showed distinct lineage with the order of phylogeny. Conclusion From our results we conclude that, among all the bacterial translation factors, elongation and release factors are more conserved in terms of their pI values in comparison to initiation and recycling factors. Acidic properties of these factors are independent of habitat, nature, or the phylogeny of the bacterial species. Furthermore; irrespective of the different shapes, sizes, and functions of the elongation and release factors, possession of their strictly acidic pI values indicate that the acidic nature of these factors is a necessary criterion, perhaps to interact into the partially enclosed rRNA rich inter-subunit space of the translating 70S ribosome.

Structure, Morphological, and Physicochemical Characteristics of a New Composite Coagulant Made From Polyaluminium Chloride and Agro-waste of Tapioca Peel

A combination of a metal coagulant with an organic polymer can complement both the outstanding and flaw properties of the separate elements. A novel composite coagulant of polyaluminium chloride (PAC)-tapioca peel extract powder (TPP) called PACTPP with different weights ratio was prepared in this study. In the preliminary study, PACTPPg at the weight/weight ratio of TPP/Al=3.71 was selected as the optimum one based on the performance in treating wastewater sample of landfill leachate. Through all characterisation analyses, it revealed that the novel composite reagent exhibits better coagulant properties when compared with the individual coagulants of PAC and TPP. It was characterised that PACTPPg had combined the best benefits from PAC and TPP, with an acidic property of pH 3.45, the low charge density of 3.45 mV, the higher molecular weight of 1.59 × 107 g/mol, the bigger particle size of 4.528 × 104 d.mn, and a longer connected and compact structure. Through Fourier transform infrared (FTIR) and X-ray diffraction (XRD) analyses, PACTPPg was identified to comprise new chemical compounds, i.e., the functional groups of ketones, aldehydes, and alkanes in a semi-formed crystalline phase. Based on the comparison study, it can be concluded that PACTPPg showed a correlation to encompass the complex interpenetration networks rather than just a simple mechanical mixing of raw materials.

Acidity Suppression of Hole Transport Layer via Solution Reaction of Neutral PEDOT:PSS for Stable Perovskite Photovoltaics

Poly(3,4-ethylenedioxythiophene): poly(4-styrenesulfonate) (PEDOT:PSS) is typically used for hole transport layers (HTLs), as it exhibits attractive mechanical, electrical properties, and easy processability. However, the intrinsically acidic property can degrade the crystallinity of perovskites, limiting the stability and efficiency of perovskite solar cells (PSCs). In this study, inverted CH3NH3PbI3 photovoltaic cells were fabricated with acidity suppressed HTL. We adjusted PEDOT:PSS via a solution reaction of acidic and neutral PEDOT:PSS. And we compared the various pH-controlled HTLs for PSCs devices. The smoothness of the pH-controlled PEDOT:PSS layer was similar to that of acidic PEDOT:PSS-based devices. These layers induced favorable crystallinity of perovskite compared with acidic PEDOT:PSS layers. Furthermore, the enhanced stability of pH optimized PEDOT:PSS-based devices, including the prevention of degradation by a strong acid, allowed the device to retain its power conversion efficiency (PCE) value by maintaining 80% of PCE for approximately 150 h. As a result, the pH-controlled HTL layer fabricated through the solution reaction maintained the surface morphology of the perovskite layer and contributed to the stable operation of PSCs.