In this study, twenty-six core shale samples were collected from the marine Lower Paleozoic shale in a well in the northeastern margin of the Yangtze Platform. Analyses of TOC content, mineral composition, major elements, along with trace and rare earth elements were conducted on the samples. The results were used to investigate the depositional conditions and their effects on organic matter accumulation and preservation. Generally, the sedimentation period of Niutitang Formation shale was in a cold and arid climate with anoxic marine environments, while the shale from Wufeng-Longmaxi Formation was formed in a warm and humid climate with oxic marine environments. In addition, the Wufeng-Longmaxi and Niutitang formations are characterized by low paleo-productivity. The organic matter enrichment for shale in this study could be simultaneously controlled by paleo-redox state and paleo-productivity. Organic matter enrichment of the Niutitang shale is mainly driven by preservation rather than productivity, while the dominant driving factor is the opposite for the Wufeng-Longmaxi shale. Additionally, palaeoclimate and terrestrial influx intensity were found to significantly impact the organic matter enrichment in the Wufeng-Longmaxi shale. The findings have implications for the understanding of the sedimentary processes, organic matter enrichment and preservation and shale gas potential of the study area.

Food packaging bags are fast-moving consumer products with large output and fast production speed. Instant noodle bags need to be printed on the production date and number before packaging the food. For the possible date or code printing error, character sticking, incompleteness, etc., the correctness of the characters cannot be judged in real time by the human eye. A set of automatic recognition characters and detection systems are used to binarize, filter and tilt the picture, and use image morphology and horizontal and vertical projection to segment a single character. BP neural network is used to identify the character and compare it to the template to obtain the degree of defect and compare it with the threshold to determine whether the character is qualified. The detection speed of the system can reach 3 images per second, which can realize real-time recognition and detection of characters, so as to eliminate non-conforming products in time.

Rationale: Position-Specific (PS) δ13C values of propane has proven its ability to provide valuable information on evolution history of natural gases. Two major approaches to measure PS δ13C values of propane are quantitative NMR (qNMR) and GC-Py(rolysis)-GC-IRMS. The qNMR has verified measurement accuracy, however, required large sample size and long experimental time limit its applications. The GC-Py-GC-IRMS is more versatile method with small sample size, but its accuracy has not been demonstrated. Methods: We measured PS δ13C values of propane from nine natural gases, using the both methods and evaluated the accuracy of GC-Py-GC-IRMS method. Results: The results show that large carbon isotope fractionations occurred for the both terminal and central carbons within propane during pyrolysis. The isotope fractionations during the pyrolysis are reproducible at optimum conditions, but vary between the two GC-Py-GC-IRMS systems tested, affected by experimental conditions (e.g., pyrolysis temperature, flow rate, and reactor conditions). Conclusions: Therefore, it is necessary to evaluate and calibrate each GC-Py-GC-IRMS system using propane gases whose PS δ13C values are accurately determined. This study also highlights a need of PS isotope standards for propane and other molecules.

Photocatalytic degradation technology is an important tool for treating trichloroethylene (TCE) pollution in water bodies. While previous studies have focused on catalyst optimization and degradation kinetics for trichloroethylene (TCE) photocatalysis, the systematic impact of environmental conditions on carbon isotope effects (ε) and their mechanistic implications remains poorly understood. This limits the reliability of quantitative isotope analyses in field applications. We conducted a series of laboratory experiments on the photocatalytic degradation of TCE to investigate the kinetic and isotopic effects under different conditions. Increasing the concentration of TCE, anions (NO₃⁻ and HCO₃⁻), and cations (Mg²⁺ and Ca²⁺) decreased the photocatalytic degradation of TCE. O₂ will increase the degradation efficiency of TCE. The dose required to achieve maximum photocatalytic efficiency varies for different types of catalysts, which needs to be determined on a case-by-case basis. TCE photocatalytic degradation had a small carbon isotope effect (ε = −2.0 ± 0.2‰ to −3.2 ± 0.5‰), which was slightly affected by the catalyst dosage and species (TiO₂ and ZnO), and concentrations of TCE, O₂, and inorganic ions (NO₃⁻, HCO₃⁻, Mg²⁺, and Ca²⁺). The ε values are stable and reproducible and relatively insensitive to our selected environmental factors in this study, which can reduce the uncertainty of applying stable carbon isotope enrichment factors to quantify the photocatalytic reaction for remediation of TCE contaminated sites.