Linkages between nitrogen cycling, nitrogen isotopes, and environmental properties in paleo-lake basins

This work was funded by the National Natural Science Foundation of China (no. 41830425). E.E. Stüeken acknowledges funding from a Natural Environment Research Council grant (no. NE/V010824/1).The linkages between nitrogen cycling, nitrogen isotopes, and environmental properties are fundamental for reconstructing nitrogen biogeochemistry. While the impact of ocean redox changes on nitrogen isotopes is relatively well understood, it is poorly known how nitrogen responds to changes in pH and salinity. To fill the knowledge gap, we explore the effects of these environmental parameters using a well-controlled set of samples from Carboniferous−Paleogene lake sediments in China. Our results show that the threshold of 10−12‰ in δ15N works to distinguish alkaline (pH > 9) from circum-neutral conditions. Elevated Mo levels in the alkaline samples support the idea of NH3 volatilization from a reducing water column in an alkaline setting. For non-alkaline lakes, δ15N values tend to be higher (up to +10‰) in more saline, anoxic settings, which is attributed to either the expansion of stagnant anoxic waters spurring water-column denitrification or a shift from plant-based toward more microbially dominated ecosystems or both. Our results imply that salinity-induced redox stratification and basicity can alter nitrogen biogeochemical cycling beyond what is shown by the marine nitrogen isotope record alone. This finding will result in an improved understanding of the dynamic controls of δ15N in sediments and lead to better biogeochemical interpretations of paleo-environmental conditions from unknown environmental settings on Earth and beyond Earth.PostprintPeer reviewe

User-centered Evaluation of Metadata Schema for Murals: Preliminary Results from A Survey Study

There has not been a well-accepted metadata schema for murals as an important type of cultural heritage. This paper reports an ongoing study and preliminary results on evaluating a draft metadata schema of murals from the end-user perspective. Based on the results of an earlier interview-based evaluation, a questionnaire was designed and 185 effective responses were collected from potential users. “Work type”, “Title”, and “Creation date” were identified as the most important metadata elements, and the most useful elements for supporting the searching, browsing, and organizing information about murals. In summary, findings of this study contribute to polishing the design of the metadata schema for murals

Efficient dealkalization of red mud and recovery of valuable metals by a sulfur-oxidizing bacterium

Red mud (RM) is a highly alkaline polymetallic waste generated via the Bayer process during alumina production. It contains metals that are critical for a sustainable development of modern society. Due to a shortage of global resources of many metals, efficient large-scale processing of RM has been receiving increasing attention from both researchers and industry. This study investigated the solubilization of metals from RM, together with RM dealkalization, via sulfur (S(0)) oxidation catalyzed by the moderately thermophilic bacterium Sulfobacillus thermosulfidooxidans. Optimization of the bioleaching process was conducted in shake flasks and 5-L bioreactors, with varying S(0):RM mass ratios and aeration rates. The ICP analysis was used to monitor the concentrations of dissolved elements from RM, and solid residues were analyzed for surface morphology, phase composition, and Na distribution using the SEM, XRD, and STXM techniques, respectively. The results show that highest metal recoveries (89% of Al, 84% of Ce, and 91% of Y) were achieved with the S(0):RM mass ratio of 2:1 and aeration rate of 1 L/min. Additionally, effective dealkalization of RM was achieved under the above conditions, based on the high rates (>95%) of Na, K, and Ca dissolution. This study proves the feasibility of using bacterially catalyzed S(0) oxidation to simultaneously dealkalize RM and efficiently extract valuable metals from the amassing industrial waste

Effects on global warming by microbial methanogenesis in alkaline lakes during the Late Paleozoic Ice Age (LPIA)

This work was jointly funded by the National Natural Science Foundation of China (Grant Nos . 42230808, 42203055 and 41830425) and PetroChina Science and Technology Major project (Grant No. 20 21DJ0108).Methane (CH4) is an important greenhouse gas, but its behavior and influencing factors over geological time scales are not sufficiently clear. This study investigated the Late Paleozoic Ice Age (LPIA), which is thought to have experienced an interval of rapid warming at ca. 304 Ma, that may have been analogous to modern warming. To explore possible causes of this warming event, we investigated ancient alkaline lakes in the Junggar Basin, northwestern China. Results show that microbial CH4 cycling here was strong, as evidenced by carbonate δ13C (δ13Ccarb) values of >5‰, ∼+0.6‰ offsets between pristane δ13C (δ13CPr) and phytane δ13C (δ13CPh) values, a 3β-methylhopane index of 9.5% ± 3.0%, and highly negative δ13C values of hopanes (−44‰ to −61‰). Low sulfate concentrations in the alkaline lakes made methanogenic archaea more competitive than sulfate-reducing bacteria, and the elevated levels of dissolved inorganic carbon promoted methanogenesis. Biogenic CH4 emissions from alkaline lakes, in addition to CO2, may have contributed to rapid climate warming.PostprintPeer reviewe

The histone deacetylase inhibitor valproic acid alters growth properties of renal cell carcinoma in vitro and in vivo

Histone deacetylase (HDAC) inhibitors represent a promising class of antineoplastic agents which affect tumour growth, differentiation and invasion. The effects of the HDAC inhibitor valproic acid (VPA) were tested in vitro and in vivo on pre-clinical renal cell carcinoma (RCC) models. Caki-1, KTC-26 or A498 cells were treated with various concentrations of VPA during in vitro cell proliferation 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays and to evaluate cell cycle manipulation. In vivo tumour growth was conducted in subcutaneous xenograft mouse models. The anti-tumoural potential of VPA combined with low-dosed interferon-α (IFN-α) was also investigated. VPA significantly and dose-dependently up-regulated histones H3 and H4 acetylation and caused growth arrest in RCC cells. VPA altered cell cycle regulating proteins, in particular CDK2, cyclin B, cyclin D3, p21 and Rb. In vivo, VPA significantly inhibited the growth of Caki-1 in subcutaneous xenografts, accompanied by a strong accumulation of p21 and bax in tissue specimens of VPA-treated animals. VPA–IFN-α combination markedly enhanced the effects of VPA monotherapy on RCC proliferation in vitro, but did not further enhance the anti-tumoural potential of VPA in vivo. VPA was found to have profound effects on RCC cell growth, lending support to the initiation of clinical testing of VPA for treating advanced RCC

Mid-IR heterogeneous silicon photonics

In this paper we discuss silicon-based photonic integrated circuit technology for applications beyond the telecommunication wavelength range. Silicon-on-insulator and germanium-on-silicon passive waveguide circuits are described, as well as the integration of III-V semiconductors, IV-VI colloidal nanoparticle films and GeSn alloys on these circuits for increasing the functionality. The strong nonlinearity of silicon combined with the low nonlinear absorption in the mid-infrared is exploited to generate picosecond pulse based supercontinuum sources and optical parametric oscillators that can be used as spectroscopic sensor sources

Localization of Non-Linearly Modeled Autonomous Mobile Robots Using Out-of-Sequence Measurements

This paper presents a state of the art of the estimation algorithms dealing with Out-of-Sequence (OOS) measurements for non-linearly modeled systems. The state of the art includes a critical analysis of the algorithm properties that takes into account the applicability of these techniques to autonomous mobile robot navigation based on the fusion of the measurements provided, delayed and OOS, by multiple sensors. Besides, it shows a representative example of the use of one of the most computationally efficient approaches in the localization module of the control software of a real robot (which has non-linear dynamics, and linear and non-linear sensors) and compares its performance against other approaches. The simulated results obtained with the selected OOS algorithm shows the computational requirements that each sensor of the robot imposes to it. The real experiments show how the inclusion of the selected OOS algorithm in the control software lets the robot successfully navigate in spite of receiving many OOS measurements. Finally, the comparison highlights that not only is the selected OOS algorithm among the best performing ones of the comparison, but it also has the lowest computational and memory cost

Epitaxial growth of topological insulator Bi2Se3 film on Si(111) with atomically sharp interface

Atomically sharp epitaxial growth of Bi2Se3 films is achieved on Si (111) substrate with MBE (Molecular Beam Epitaxy). Two-step growth process is found to be a key to achieve interfacial-layer-free epitaxial Bi2Se3 films on Si substrates. With a single-step high temperature growth, second phase clusters are formed at an early stage. On the other hand, with low temperature growth, the film tends to be disordered even in the absence of a second phase. With a low temperature initial growth followed by a high temperature growth, second-phase-free atomically sharp interface is obtained between Bi2Se3 and Si substrate, as verified by RHEED (Reflection High Energy Electron Diffraction), TEM (Transmission Electron Microscopy) and XRD (X-Ray Diffraction). The lattice constant of Bi2Se3 is observed to relax to its bulk value during the first quintuple layer according to RHEED analysis, implying the absence of strain from the substrate. TEM shows a fully epitaxial structure of Bi2Se3 film down to the first quintuple layer without any second phase or an amorphous layer.Comment: 20 pages, 7 figure