This volume describes the fundamentals and techniques necessary for Lamb-wave-based damage identification. This damage assessment method offers efficient structural failure detection which lowers ...maintenance costs and increases safety benefits.
The Sichuan-Yunnan-Guizhou Pb-Zn metallogenic province (SYGMP) is an important region for Pb-Zn resources in China. However, considerable controversy remains as to whether the Pb-Zn deposits are ...Mississippi Valley Type (MVT). The Maozu deposit, a typical example of the carbonate-hosted Pb-Zn deposits in the SYGMP, occurs in the late Ediacaran Dengying Formation and its ore bodies are divided into three types: lower layer (LL), vein layer (VL), and upper layer (UL) ore bodies based on their spatial relationship. In this study, laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) was used to systematically analyze the trace-element compositions of sphalerite and galena in these three ore bodies. The results show that sphalerite is characterized by Cd and Ge enrichment; Fe, Mn, and Co depletion; and local In and Sn enrichment. Most of these elements likely appear as solid solutions in sphalerite and show a wide compositional variation, which is probably related to the medium- and low-temperature mixing of the ore-forming fluids. The local enrichment of In and Sn is likely attributed to the long-distance migration of ore-forming fluids through In-Sn-bearing volcaniclastic rocks. In vs. Sn and (Cu+Sb) vs. (Ag+Ge) show strong correlations and similar element distribution in the mapped images, indicating that these elements may be incorporated into sphalerite via a coupled substitution for Zn as 2In++Sn4++2 ⇌ 5Zn2+ (=vacancies) and 4(Cu++Sb3+)+(Ge4++2Ag+)+2 ⇌ 13Zn2+. Galena is enriched in Ag and Sb with minor Cd and Se and depleted in Bi, and most of the elements may occur as solid solutions. Ag vs. Sb in galena displays a strong positive correlation, implying the coupled substitution of Ag++Sb3+ ⇌ 2Pb2+. Notably, the majority of the trace-element concentrations gradually decrease in the order LL → UL except Fe, Co, Cu, and Ge, while Fe, In, and Sn in sphalerite and Ag and Sb in galena have the highest concentration in the VL, indicating that the VL is a secondary migration channel for the ore-forming fluids. Furthermore, the trace-element compositions of the sulfides in the Maozu Pb-Zn deposit are consistent with the typical MVT deposit (hosted in the carbonate sequence) but are markedly different from sedimentary exhalative (SEDEX), volcanogenic massive sulfide (VMS) and skarn-type deposits. Based on these results, as well as the geological and geochemical characteristics of the deposit, the Maozu Pb-Zn deposit is an MVT deposit.
In this study, we successfully demonstrated that 454 pyrosequencing was a powerful approach for investigating the bacterial communities in the activated sludge, digestion sludge, influent, and ...effluent samples of a full scale wastewater treatment plant treating saline sewage. For each sample, 18,808 effective sequences were selected and utilized to do the bacterial diversity and abundance analysis. In total, 2,455, 794, 1,667, and 1,932 operational taxonomic units were obtained at 3 % distance cutoff in the activated sludge, digestion sludge, influent, and effluent samples, respectively. The corresponding most dominant classes in the four samples are
Alphaproteobacteria
,
Thermotogae
,
Deltaproteobacteria
, and
Gammaproteobacteria
. About 67 % sequences in the digestion sludge sample were found to be affiliated with the
Thermotogales
order. Also, these sequences were assigned into a recently proposed genus
Kosmotoga
by the Ribosomal Database Project classifier
.
In the effluent sample, we found high abundance of
Mycobacterium
and
Vibrio
, which are genera containing pathogenic bacteria. Moreover, in this study, we proposed a method to differentiate the “gene percentage” and “cell percentage” by using Ribosomal RNA Operon Copy Number Database.
We here report the fabrication of a core-shell WO3@ZnIn2S4 heterostructure by an interfacial seeding growth strategy, which is implemented by direct growth of ZnIn2S4 nanosheets on the surface of WO3 ...nanorods with forming a strong electronic interaction between two semiconductors that are beneficial for promoting the interfacial charge transfer. Systematic studies demonstrate that the WO3@ZnIn2S4 nanohybrids hold superior performance for photocatalytic hydrogen generation under visible light irradiation with a production rate of 3900 μmol g−1 h−1. This work provides an effective approach to construct the direct Z-scheme photocatalytic systems for efficient photocatalytic hydrogen evolution, which would be significant for the design of more direct Z-scheme system for various photocatalytic applications.
It is of increasing importance to explore new low‐cost and high‐activity electrocatalysts for oxygen reduction reaction (ORR), which have had a substantial impact across a diverse range of energy ...conversion system, including various fuel cell and metal–air batteries. Although engineering carbon nanostructures have been widely explored as a candidate class of Pt‐based ORR electrocatalysts owing to their proved high activity, outstanding stability, and ease of use, there still remains a daunting challenge to develop high activity metal‐free electrocatalysts in pH‐universal electrolyte system. Here, a reliable and controllable route amenable to prepare nitrogen‐doped porous carbon (NPC) with high yields and exceptional quality is described. The as‐prepared NPC shows advantages of high activity, high durability, and methanol‐tolerant as an efficient pH‐universal electrocatalyst for ORR, showing comparable or even better activity as compared with the commercial Pt/C catalysts not only in alkaline media but also in acidic and neutral electrolyte. Systematic electrochemical studies, combining with density functional theory calculation, demonstrate the unique nitrogen‐doping species and favorable pores in the as‐designed NPC synergistically contribute to the significantly improved catalytic activity in pH‐universal medium. The present work potentially presents an important breakthrough in developing ORR electrocatalysts for various fuel cells.
Nitrogen‐doped porous carbon (NPC) with pore size of ≈10–12 nm is developed using oxygen‐rich Zn‐metal‐organic‐framework‐74 as precursor. The optimized NPC sample shows comparable or even superior oxygen reduction reaction (ORR) activity compared with the commercial Pt/C catalysts not only in alkaline media but also in acidic and neutral electrolyte.
The grain contamination by
spp. has been a serious issue. This study exhibited the excellent antifungal effects of the essential oil compounds (EOCs) geraniol and citral against common grain ...pathogens (
and
) in vitro and in situ. The inhibitory mechanisms were also evaluated from the perspective of cell membrane permeability, reactive oxygen species (ROS) generation, and
spp. growth-related gene expression. Meanwhile, the combined effects of EOCs in the vapor phase and modified atmosphere packaging (MAP) were examined to find an alternative preservation method for controlling
spp. The results indicated that citral exhibited the antifungal activity mainly by downregulating the sporulation- and growth-related genes for both pathogens. Geraniol displayed inhibitory effectiveness against
predominantly by inducing the intracellular ROS accumulation and showed toxicity against
principally by changing cell membrane permeability. Furthermore, the synthetic effects of EOCs and MAP (75% CO₂ and 25% N₂) induced better grain quality than the current commercial fumigant AlP. These findings reveal that EOCs have potential to be a novel grain preservative for further application.
We report the fabrication of self-supported Cu/Cu2O–CuO/rGO nanowire arrays on commercial porous copper foam, which exhibit excellent activity and durability for electrochemical hydrogen evolution, ...presenting a small onset potential of 84 mV and a low overpotential of 105 mV at a current density of 10 mA cm−2.
Aerobic granular sludge (AGS), a self-immobilized microbial consortium containing different functional microorganisms, is receiving growing attention, since it has shown great technological and ...economical potentials in the field of wastewater treatment. Microbial community is crucial for the formation, stability, and pollutant removal efficiency of aerobic granules. This mini-review systematically summarizes the recent findings of the microbial community structure and function of AGS and discusses the new research progress in the microbial community dynamics during the granulation process and spatial distribution patterns of the microbiota in AGS. The presented information may be helpful for the in-depth theoretical study and practical application of AGS technology in the future.
We report a straightforward strategy to design efficient N doped porous carbon (NPC) electrocatalyst that has a high concentration of easily accessible active sites for the CO2 reduction reaction ...(CO2RR). The NPC with large amounts of active N (pyridinic and graphitic N) and highly porous structure is prepared by using an oxygen‐rich metal–organic framework (Zn‐MOF‐74) precursor. The amount of active N species can be tuned by optimizing the calcination temperature and time. Owing to the large pore sizes, the active sites are well exposed to electrolyte for CO2RR. The NPC exhibits superior CO2RR activity with a small onset potential of −0.35 V and a high faradaic efficiency (FE) of 98.4 % towards CO at −0.55 V vs. RHE, one of the highest values among NPC‐based CO2RR electrocatalysts. This work advances an effective and facile way towards highly active and cost‐effective alternatives to noble‐metal CO2RR electrocatalysts for practical applications.
A means to an N: N‐doped porous carbon (NPC) with a hierarchical porous structure and a high concentration of pyridinic‐N and graphitic‐N was prepared by calcinating a mixture of oxygen‐rich Zn‐MOF‐74 and melamine. The optimized NPC shows a high electrocatalytic activity toward CO2 reduction and high selectivity by suppressing hydrogen evolution.
Metal doped core–shell Metal‐Organic Frameworks@Covalent Organic Frameworks (MOFs@COFs) are presented as a novel platform for photocatalysis. A palladium (Pd) doped MOFs@COFs in the form of ...Pd/TiATA@LZU1 shows excellent photocatalytic performance for tandem dehydrogenation and hydrogenation reactions in a continuous‐flow microreactor and a batch system, indicating the great potential of the metal doped MOFs@COFs as a multifunctional platform for photocatalysis. Explanations for the performance enhancement are elucidated. An integrated dual‐chamber microreactor coupled with the metal doped MOFs@COFs is introduced to demonstrate a concept of an intensified green photochemical process, which can be broadly extended to challenging liquid–gas tandem and cascade reactions.
Pd doped core–shell TiATA@LZU1 is fabricated and shows excellent photocatalytic performance for hydrogenation and dehydrogenation reactions in batch and in a newly designed dual‐chamber microreactor. This indicates a great promise of metal–organic frameworks@covalent organic frameworks (MOFs@COFs) hybrids as a novel platform for efficient photocatalysis.
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