Virtual Sensing of Key Variables in the Hydrogen Production Process: A Comparative Study of Data-Driven Models.

Hydrogen is an ideal energy carrier manufactured mainly by the natural gas steam reforming hydrogen production process. The concentrations of CH4, CO, CO2, and H2 in this process are key variables related to product quality, which thus need to be controlled accurately in real-time. However, conventional measurement methods for these concentrations suffer from significant delays or huge acquisition and upkeep costs. Virtual sensors effectively compensate for these shortcomings. Unfortunately, previously developed virtual sensors have not fully considered the complex characteristics of the hydrogen production process. Therefore, a virtual sensor model, called "moving window-based dynamic variational Bayesian principal component analysis (MW-DVBPCA)" is developed for key gas concentration estimation. The MW-DVBPCA considers complicated characteristics of the hydrogen production process, involving dynamics, time variations, and transportation delays. Specifically, the dynamics are modeled by the finite impulse response paradigm, the transportation delays are automatically determined using the differential evolution algorithm, and the time variations are captured by the moving window method. Moreover, a comparative study of data-driven virtual sensors is carried out, which is sporadically discussed in the literature. Meanwhile, the performance of the developed MW-DVBPCA is verified by the real-life natural gas steam reforming hydrogen production process.

Dynamic transcriptome profiling revealed a key gene ZmJMJ20 and pathways associated with cadmium stress in maize.

Cadmium (Cd) pollution in soil poses a global concern due to its serious impacts on human health and ecological security. In plants, tremendous efforts have been made to identify some key genes and pathways in Cd stress responses. However, studies on the roles of epigenetic factors in response to Cd stress were still limited. In the study, we first gain insight into the gene expression dynamics for maize seedlings under 0 h, 12 h, and 72 h Cd stress. As a result, six distinct groups of genes were identified by hierarchical clustering and principal component analysis. The key pathways associated with 12 h Cd stress were protein modifications including protein ubiquitination, signal transduction by protein phosphorylation, and histone modification. Whereas, under 72 h stress, main pathways were involved in biological processes including phenylalanine metabolism, response to oxygen-containing compounds and metal ions. Then to be noted, one of the most highly expressed genes at 12 h under Cd treatment is annotated as histone demethylases (ZmJMJ20). The evolutionary tree analysis and domain analysis showed that ZmJMJ20 belonged to the JmjC-only subfamily of the Jumonji-C (JmjC) family, and ZmJMJ20 was conserved in rice and Arabidopsis. After 72 h of Cd treatment, the zmjmj20 mutant created by EMS treatment manifested less severe chlorosis/leaf yellowing symptoms compared with wild-type plants, and there was no significant difference in Fv/Fm and φPSII value before and after Cd treatment. Moreover, the expression levels of several photosynthesis-related down-regulated genes in EMS mutant plants were dramatically increased compared with those in wild-type plants at 12 h under Cd treatment. Our results suggested that ZmJMJ20 plays an important role in the Cd tolerance response pathway and will facilitate the development of cultivars with improved Cd stress tolerance.

Introduction of Cationic Vacancies into NiFe LDH by In Situ Etching To Improve Overall Water Splitting Performance.

Nickel-iron layered double hydroxide (NiFe LDH) is still one of the hot catalysts for electrochemical water decomposition applications, despite its drawbacks, such as intrinsic activity and poor stability. In this work, the NiFe LDH-D1 electrocatalyst with cationic vacancies is successfully prepared by alkaline etching of Zn ion-doped NiFe LDH. The tightly arranged flocculated nanosheet structure on its surface provided a large active area. The cationic vacancies formed by strong alkaline etching not only promote the conversion of active phases such as NiOOH but also strengthen the stability of the electrode and the binding ability with oxygen so that the material has excellent catalytic properties along with alkaline long-term stability. At a current density of 10 and 100 mA cm-2, NiFe LDH-D1 shows a small voltage of 1.56 and 1.94 V, and at a current density of 200 mA cm-2, it performs well in a 72 h electrochemical water decomposition stability test. The present work demonstrates a simple etching strategy for cation vacancy engineering and provides an example of the construction of efficient bifunctional electrocatalysts with long-term stability.

Transcriptome-wide identification and characterization of genes exhibit allele-specific imprinting in maize embryo and endosperm.

BACKGROUND: Genomic imprinting refers to a subset of genes that are expressed from only one parental allele during seed development in plants. Studies on genomic imprinting have revealed that intraspecific variations in genomic imprinting expression exist in naturally genetic varieties. However, there have been few studies on the functional analysis of allele-specific imprinted genes. RESULTS: Here, we generated three reciprocal crosses among the B73, Mo17 and CAU5 inbred lines. Based on the transcriptome-wide analysis of allele-specific expression using RNA sequencing technology, 305 allele-specific imprinting genes (ASIGs) were identified in embryos, and 655 ASIGs were identified in endosperms from three maize F1 hybrids. Of these ASIGs, most did not show consistent maternal or paternal bias between the same tissue from different hybrids or different tissues from one hybrid cross. By gene ontology (GO) analysis, five and eight categories of GO exhibited significantly higher functional enrichments for ASIGs identified in embryo and endosperm, respectively. These functional categories indicated that ASIGs are involved in intercellular nutrient transport, signaling pathways, and transcriptional regulation of kernel development. Finally, the mutation and overexpression of one ASIG (Zm305) affected the length and width of the kernel. CONCLUSION: In this study, our data will be helpful in gaining further knowledge of genes exhibiting allele-specific imprinting patterns in seeds. The gain- and loss-of-function phenotypes of ASIGs associated with agronomically important seed traits provide compelling evidence for ASIGs as crucial targets to optimize seed traits in crop plants.

Engineering interfacial coupling between 3D net-like Ni3(VO4)2 ultrathin nanosheets and MoS2 on carbon fiber cloth for boostinghydrogen evolution reaction.

The use of cheap and efficient electrocatalyst for the production of hydrogen is the key to solving the current energy crisis. Herein, we used a two-step hydrothermal process to fabricate noble-metal-free 3D net-like Ni3(VO4)2 ultrathin nanosheets coupled with MoS2@CFC interface. Unlike the traditional two-dimensional composite materials, Ni3(VO4)2 ultrathin nanosheets intersect with MoS2 nanosheets grown on CFC in a 3D net-like structure (Ni3(VO4)2/MoS2@CFC). Due to the mutual combination of structures and the interfacial coupling cooperation effect between Ni3(VO4)2 nanosheet and MoS2@CFC, the catalytically active area was expanded, and the intrinsic activity toward HER was significantly improved. Ni3(VO4)2/MoS2@CFC showed high activity at the industrial temperature (75 °C), with an overpotential of 77 mV (10 mA/cm2) and a 65 mV/dec Tafel slope. This material showed good stability at 0.5 M H2SO4. This work provides a heterostructure scheme for the construction of a novel noble metal-free electrocatalyst to promote hydrogen evolution reaction.

A Mini Review of the Preparation and Photocatalytic Properties of Two-Dimensional Materials.

The successful preparation and application of graphene shows that it is feasible for the materials with a thickness of a single atom or few atomic layers to exist stably in nature. These materials can exhibit unusual physical and chemical properties due to their special dimension effects. At present, researchers have made great achievements in the preparation, characterization, modification, and theoretical research of 2D materials. Because the structure of 2D materials is often similar, it has a certain degree of qualitative versatility. Besides, 2D materials often carry good catalytic performance on account of their more active sites and adjustable harmonic electronic structure. In this review, taking 2D materials as examples [graphene, boron nitride (h-BN), transition metal sulfide and so on], we review the crystal structure and preparation methods of these materials in recent years, focus on their photocatalyst properties (carbon dioxide reduction and hydrogen production), and discuss their applications and development prospects in the future.

Design of nickel cobalt molybdate regulated by boronizing for high-performance supercapacitor applications.

Nickel-cobalt-based molybdates have been intensively investigated because of their high theoretical specific capacitance and multifarious oxidation states. Here, we have successfully synthesized hierarchical structures (Ni3B/Ni(BO2)2@NixCoyMoO4) by boronizing NixCoyMoO4 nanosheets on flexible carbon cloth substrates. Benefitting from the synergistic effect among Ni3B, Ni(BO2)2 and NixCoyMoO4 in hybrid architectures, the electrode material possesses higher capacity of 394.7 mA h g-1 at 1 A g-1 and a good rate performance (309.5 mA h g-1 maintained at 20 A g-1). Then, a hybrid supercapacitor assembled with Ni3B/Ni(BO2)2@NixCoyMoO4 and activated carbon as the positive and the negative electrode, displays a high specific capacitance of 370.7 F g-1 at 1 A g-1 (210 F g-1 at 10 A g-1), a high voltage of 1.7 V, and a high energy density of 131.8 W h kg-1 at the power density of 800 W kg-1 (still 74.7 W h kg-1 maintained at 8000 W kg-1). This study widens the research scope of boronizing pseudocapacitance materials and reveals a high application potential of Ni3B/Ni(BO2)2@NixCoyMoO4 for energy storage devices in the future.