Improvements of X-band and Q-band EPR /ENDOR spectrometers Studies of ferritin iron nitrosyl and copper cis, cis-1,3,5-triaminocyclohexane chloride complexes, and the application of Q -band EPR to the dating of fossil teeth

Several modifications were made on a Varian Q-band EPR/ENDOR spectrometer, including the installation of a microwave amplifier in the E110 bridge, design and assembly of a new cavity coupler, addition of frequency counting capability, as well as other useful minor changes. The performance of the spectrometer was improved in signal-to-noise ratio, convenience of tuning and operation and accuracy of g-value and hyperfine coupling measurements. The signal-to-noise ratio was increased by a factor of six. Improvements were also achieved with our X-band EPR/ENDOR spectrometer by design and assembly of a new printed ENDOR coil for use in a TE104 rectangular cavity. The Dewar and sample holder were changed to accommodate EPR tubes of 5 mm o.d. The ENDOR signal-to-noise ratio of a sucrose standard sample was increased by a factor of three by these changes. 1H ENDOR studies of ferritin iron nitrosyl complexes and other model complexes were carried out with the new ENDOR system. The proton ENDOR signals of ferritin iron nitrosyl complexes were first observed in this laboratory. Molecular modeling calculations and the equations derived for the iron nitrosyl complexes enable one to undertake a complete ENDOR data analysis. The ENDOR studies suggested that the local structure of the iron site in the ferritin iron nitrosyl complex was identical to that of a model complex of penicillamine with the iron atom coordinated to a sulphur atom of a cysteine residue, a nitrogen atom in the protein backbone and two nitric oxide radicals. EPR/ENDOR studies of copper cis,cis-1,3,5-triaminocyclohexane have shown the complexes to have a rhombic magnetic symmetry in powders, but axial symmetry in aqueous solution. When the complex was prepared in methanol, it retained its molecular configuration as in the crystal. However, when prepared in aqueous solution, two water molecules might replace one or two of the chloride ions in the equatorial plane of the complex. The sample in aqueous solution had covalent in-plane sigma bonding. The out-plane pi bonds and the in-plane pi bond were ionic for the aqueous sample. Finally, Q-band EPR studies of fossil tooth enamel demonstrated that X-band EPR could be used for routine dating of fossil teeth samples by slightly over modulating the overlapping signals of the dating and interfering radical centers. The interfering peak in some of the fossil tooth enamel samples appears to arise from a slight structural deformation of the radical center in hydroxyapatite. The age of the measured fossil teeth sample was determined to be about 1400 years old

FE-RetinaNet: Small Target Detection with Parallel Multi-Scale Feature Enhancement

Because small targets have fewer pixels and carry fewer features, most target detection algorithms cannot effectively use the edge information and semantic information of small targets in the feature map, resulting in low detection accuracy, missed detections, and false detections from time to time. To solve the shortcoming of insufficient information features of small targets in the RetinaNet, this work introduces a parallel-assisted multi-scale feature enhancement module MFEM (Multi-scale Feature Enhancement Model), which uses dilated convolution with different expansion rates to avoid multiple down sampling. MFEM avoids information loss caused by multiple down sampling, and at the same time helps to assist shallow extraction of multi-scale context information. Additionally, this work adopts a backbone network improvement plan specifically designed for target detection tasks, which can effectively save small target information in high-level feature maps. The traditional top-down pyramid structure focuses on transferring high-level semantics from the top to the bottom, and the one-way information flow is not conducive to the detection of small targets. In this work, the auxiliary MFEM branch is combined with RetinaNet to construct a model with a bidirectional feature pyramid network, which can effectively integrate the strong semantic information of the high-level network and high-resolution information regarding the low level. The bidirectional feature pyramid network designed in this work is a symmetrical structure, including a top-down branch and a bottom-up branch, performs the transfer and fusion of strong semantic information and strong resolution information. To prove the effectiveness of the algorithm FE-RetinaNet (Feature Enhancement RetinaNet), this work conducts experiments on the MS COCO. Compared with the original RetinaNet, the improved RetinaNet has achieved a 1.8% improvement in the detection accuracy (mAP) on the MS COCO, and the COCO AP is 36.2%; FE-RetinaNet has a good detection effect on small targets, with APs increased by 3.2%

Fracture Modeling of Deep Tight Sandstone Fault-Fracture Reservoir Based on Geological Model and Seismic Attributes: A Case Study on Xu 2 Member in Western Sichuan Depression, Sichuan Basin

With significant geological reserves and high resource abundance, the Xujiahe Formation in the Western Sichuan Depression is considered a key target for natural gas exploration and development in continental clastic rocks within the Sichuan Basin. However, this formation remains underdeveloped. Critical to forming “sweet spots” of tight reservoir is the presence of fractures. Based on available data sources, including core samples, well logs, and outcrop data, we utilized a combination of geophysical and geological modeling techniques to clarify the characteristics of effective fractures in tight gas reservoirs. This allowed us to construct a geological model of a tight sandstone fault-fracture gas reservoir in the Xu 2 Member of the Xujiahe Formation located in the Xinchang area, which represents a fault-fracture reservoir formed by high-angle faulting-derived fractures and controlled by the S-N trending fault. With this model, a variety of seismic attributes, including likelihood and entropy, was used to predict the fault-fracture reservoir. Furthermore, geological information, well logs, and seismic attributes were integrated for characterizing the fractures of different scales. The cutoff on various attributes for characterizing the fault-fracture reservoir was defined, and the distribution of the fault-fracture reservoir was delineated. By using the geological modeling technique, the fracture model of the fault-fracture reservoir comprising natural fractures at different scales was built. This model provides further guidance for the exploration and development of the Xu 2 Member tight gas reservoirs in the Xinchang area and, as demonstrated by drilling results, has achieved remarkable effects in practice. This approach has shown good performance in characterizing fracture models. However, due to the complexity of fractures and the discrepancy between the scale of fractures and the scale that can be predicted by geophysical methods, there may still be some uncertainties associated with this method

Low-Order Radial Modal Test and Analysis of Drive Motor Stator

For a driving motor stator of EDU (Electric Drive Unit) intelligent electric transmission of a domestic plug-in hybrid electric vehicle, modal tests are performed on the motor stator with or without motor shell. Either the hammering method or the frequency sweeping method is used in the test. The modal frequencies, modal shapes, and damping ratios of the first five orders that meet the requirements of the modal confidence criterion are obtained. The influence of the motor shell on the low-order radial modal of the motor stator is discussed. The results show that similar results are obtained in the modal parameter estimation respectively using the hammering method and the frequency sweeping method. They can both be used for low-order radial modal test of the motor stator. The motor stator without shell exhibits a linear structure in the frequency domain. Each modal frequency obtained by the frequency sweeping method is slightly higher than that obtained by the hammering method

Peanut Shell Biochar’s Effect on Soil Physicochemical Properties and Salt Concentration in Highly Saline-Sodic Paddy Fields in Northeast China

Soil salinization is a major ecological threat to crop growth and production. Biochar addition can alleviate the negative impacts of saline-sodic stress in crops. Here, a two-year field experiment was conducted in a highly saline-sodic paddy field to evaluate the response of soil physico-chemical properties, ionic concentration, and rice yield to biochar applications. The soil was amended with peanut shell biochar as follows: zero biochar (B0), 33.75 t ha−1 (B1), 67.5 t ha−1 (B2), and 101.25 t ha−1 (B3). Biochar significantly reduced soil bulk density (BD), while it markedly increased total porosity (TP) and saturated hydraulic conductivity (Ks). Furthermore, biochar markedly decreased the Na+ concentration, Na+/K+ ratio, Na+/Ca2+ ratio, HCO3-, and CO32- while it increased the concentrations of K+, Ca2+, and Mg2+. Biochar significantly decreased the electrical conductivity of soil saturation extract (ECe). The exchangeable sodium percentage (ESP) of B1, B2, and B3 were 53.6%, 62.3%, and 71.0% lower, respectively, than that of B0, and the corresponding decrease in sodium adsorption ratio (SARe) was 51.2%, 58.1%, and 60.5%. Biochar had no effect on the soil pH but significantly increased the soil cation exchange capacity (CEC). The rice biomass yield, grain yield, and harvest index significantly increased after biochar application