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To analyze the stage changing quality of small and medium-sized tractors equipped with hydro-mechanical continuously variable transmission (HMCVT) in the process of power changing, based on a HMCVT with continuously variable characteristic parameters, the traditional gear planetary transmission structure was changed into the traction planetary transmission structure, and a multi-stage HMCVT system was proposed. Considering the influence of changing time and displacement ratio of the hydraulic system on the stage changing quality, AMESim modeling and simulation analysis of the multi-stage HMCVT system were carried out by adding a variable concerning which the characteristic parameters of the traction planetary array were continuously changing. When the change period t0=0.8 s was set in the simulation, multi-parameter adjustment analysis was carried out on the three evaluation indexes of the change period quality, such as velocity drop, impact degree and sliding power, in the characteristic parameter k 1.5-2. The design of the three-stage HMCVT system can reduce the maximum sliding power by 25.6% or the maximum impact degree by 20.84% by changing the value of the characteristic parameter k in the L and H stages. By changing the value of the characteristic parameter k in the S and L sections, the sliding work can be reduced by 6.68%, but the impact of changing the characteristic parameter k on the impact degree changes within 1%. The overall velocity drop will increase with the increase of the characteristic parameter k. The research results can provide reference for further improving the stage changing quality.

The small-loop transient electromagnetic method (TEM) refers to a system in which the coil frame length or diameter is less than 2 m. Due to the inductive effects of the multi-turn coils used for both transmission and reception, the induced electromotive force in the measuring coil increases, causing a reduction in the decay rate and an extension of the shutoff time. This results in coupling between the primary and secondary fields in early-time signals, making them difficult to separate and creating a detection blind spot in the shallow subsurface. The opposing coil TEM transmission and reception method can significantly reduce early-time signal distortion caused by coil inductance. However, this approach is constrained by the physical symmetry of the coil dimensions, which makes it challenging to achieve balance in a zero-field space. By performing both forward and reverse measurements at the same location using the opposing coil setup and calculating the difference between the signals, the inductive coupling between coils at the measurement site can theoretically be eliminated. This eliminates the induced potential of the TEM signal, enhancing the induced electromotive force from the formation. As a result, more accurate resistivity values are obtained, detection blind spots are eliminated, and the resolution in shallow TEM exploration is improved. Field experiments were conducted to validate the method on both high-resistivity and low-resistivity anomalies. The results demonstrated that this method effectively identified a high-resistivity corrugated pipe at a depth of 1.2 m and two low-resistivity gas pipelines at a depth of 2 m, thereby essentially eliminating detection blind spots in the shallow subsurface. [ABSTRACT FROM AUTHOR]

Data processing techniques in transient electromagnetic (TEM) methods face numerous challenges, such as the problem of 3-D imaging and the demand for new data processing techniques arising from the development of small-loop TEM devices. We have developed an imaging algorithm based on gradient features derived from TEM data to address these challenges. We found that normalising the gradient field of TEM responses under appropriate background conditions enables imaging of the target. Numerical experiments conducted under theoretical models have validated the feasibility of this approach and highlighted the significance of background fields. We further designed more complex models and achieved 3-D imaging of synthetic data within seconds, demonstrating the method's high efficiency and applicability to high-dimensional data. Subsequently, we applied the algorithm to challenging small-loop TEM data and demonstrated its superior performance compared to the inversion method, which presents a novel approach for processing data from small-loop TEM devices. This study demonstrates that the algorithm possesses characteristics of high efficiency and wide applicability, suitable for TEM data from various dimensions and types of devices. Furthermore, it holds promising potential in assisting the enhancement of the efficiency of the three-dimensional inversion of TEM data. [ABSTRACT FROM AUTHOR]

Objective We compared the cross-sectional areas of the duodenum to the distal small intestine during early gestation to determine if there is a difference in age for recanalization. Methods Serial sagittal sections of six fetuses of gestational age (GA) 8-10 weeks were examined morphologically to compare the degree of recanalization of the duodenum with to the more distal small intestine. Results At GA 8-9 weeks, the duodenum had more epithelial plugs and vacuoles with no or narrower spaces compared to the distal small bowel. Quantitative assessment at GA 10 weeks showed that the cross-sectional area of the duodenal cavity was significantly less than the distal small bowel. Conclusion The development and recanalization of vacuoles in the duodenum occurs later than the jejunum and ileum may be involved in the more frequent development of atresia/stenosis of the duodenum compared to more distal gastrointestinal tract. [ABSTRACT FROM AUTHOR]

Guite (IMA2017-080), Co3O4, is a new mineral species and an important economic mineral found in the Sicomines copper-cobalt mine, located ~11 km southwest of Kolwezi City, Democratic Republic of Congo. The mineral occurs as a granular agglomerate, 50 to 500 μm in size, and is associated closely with heterogenite in a quartz matrix. Guite is opaque, has a dark grey colour with metallic lustre and a black streak. In reflected light microscopy, it is white with no internal reflections. The reflectance values (in air, R in %) are: 27.0 (470 nm); 25.6 (546 nm); 25.2 (589 nm), and 24.6 (650 nm). The average of 20 electron-microprobe analyses is Co 71.53, Cu 0.58, Mn 0.67, Si 0.25, O 26.78, total 99.82 wt.%, corresponding to the empirical formula calculated on the basis of 4 O apfu: (Co2+0.92Cu2+0.02Si4+0.02)Σ0.96(Co3+1.98Mn3+0.03)Σ2.01O4.00, with Co2+ and Co3+ partitioned using charge balance. The ideal formula is Co2+Co3+2O4. Guite is cubic with space group Fd $\bar{3}$ m. The unit cell parameters refined from the single crystal X-ray diffraction data are: a = 8.0898(1) Å, V = 529.436(11) Å3 and Z = 8. The calculated density of guite is 6.003 g/cm3. The eight strongest observed powder X-ray diffraction lines [d in Å (I/I0) (hkl)] are: 4.6714 (16.7) (111), 2.8620 (18.4) (220), 2.4399 (100) (311), 2.3348 (10.4) (222), 2.0230 (24.8) (400), 1.5556 (26.3) (511, 333), 1.4296 (37.7) (440) and 1.0524 (10.1) (731, 553). The crystal structure of guite was determined by single-crystal X-ray diffraction and refined to R = 0.0132 for 3748 (69 unique) reflections. Guite has a typical spinel-type structure with Co2+ in tetrahedral coordination with a Co2+–O bonding length of 1.941(1) Å, and Co3+ in octahedral coordination with a Co3+–O bonding length of 1.919(1) Å. The structure is composed of cross-linked framework of chains of Co3+–O6 octahedra sharing the equilateral triangle edges (2.550 Å) in three directions [0 1 1], [1 1 0], [1 0 1] with Co2+ filling the tetrahedral interstices among the chains. Guite is named in honour of Prof. Xiangping Gu (1964–). [ABSTRACT FROM AUTHOR]

A study has been conducted to examine the crystal structures of human calcineurin, an important protein in T-cell activation, and the human binding protein complex, FKBP12-FK506, which inhibit calcineurin after association with cytoplasmic binding proteins. Electron microscopy showed that an autoinhibitory element binds calcineurin at the Zn/Fe-containing active site to induce nucleophilic attack on the substrate phosphate by a metal-activated water molecule. Since the auto-inhibitory element is displaced in the FK-506-calcineurin complex, the protein complex is forced to share a binding site with inhibitors of calcineurin.

Microcystin‐leucine arginine (MC‐LR) is a cyclic heptapeptide, produced by aquatic cyanobacteria such as microcystis, with strong reproductive toxicity which poses greater threat to the reproductive abilities of humans and animals. By exploring the role of trimethylation of histone H3 at lysine 4 (H3K4me3) and the role of oxidative stress in MC‐LR‐induced apoptosis in testicular Sertoli cells in Sprague‐Dawley (SD) rats, this study indicated that MC‐LR increased the expression levels of apoptosis‐related genes by raising the levels of H3K4me3. 5′‐Deoxy‐5′‐methylthioadenosine (MTA), the inhibitor of H3K4me3, reduced apoptosis, indicating for the first time that epigenetic modification is closely related to the testicular reproductive toxicity induced by MC‐LR. MC‐LR also induced oxidative stress by stimulating the generation of reactive oxygen species (ROS), and subsequently triggering mitochondria‐mediated apoptotic pathway by decreasing mitochondrial membrane potential and increasing the levels of Bax, Bcl‐2, Caspase‐3, and so on. MC‐LR‐induced apoptosis of testicular cells could be decreased after pretreatment with oxidative stress inhibitor N‐acetyl‐cysteine (NAC). Furthermore, the pathological damage to mitochondria and testes were observed in SD rats. These results show that MC‐LR can induce apoptosis by raising the levels of H3K4me3, and pretreatment with MTA can ameliorate the MC‐LR‐induced apoptosis of cocultured cells by lowering the levels of H3K4me3. Furthermore, NAC has a protective effect on MC‐LR‐induced apoptosis of testicular cells in SD rats by inhibiting the oxidative stress. [ABSTRACT FROM AUTHOR]

Microcystin‐LR (MC‐LR), a potent endotoxin, can induce reproductive toxicity. In order to investigate the role and mechanisms of apoptosis (p53‐dependent and mitochondrial pathways) of germ cells induced by MC‐LR, the co‐cultured primary Sertoli‐germ cells from Sprague‐Dawley rats were used for the experiments. Expression levels of proteins, genes, and mitochondrial membrane potential (MMP) were obtained after exposing co‐cultured Sertoli‐germ cells to MC‐LR with or without the addition of the p53 inhibitor, pifithrin‐α (PFT‐α), and MMP inhibitor, cyclosporin A (CsA). Results indicated that MC‐LR could activate p53‐dependent pathway‐associated proteins in Sertoli‐germ cells, leading to a decrease in MMP (indicating the opening of mitochondrial permeability transition pore [mPTP] and the release of Cytochrome‐c [Cyt‐c]) from the mitochondria into the cytoplasm and eventually the induction of apoptosis. PFT‐α inhibited the expression ofp53, ameliorated the MMP of the co‐cultured Sertoli‐germ cells, and prevented the release of Cyt‐c from the mitochondria into the cytoplasm, which reduces the occurrence of apoptosis. Similarly, the decreased release of Cyt‐c from the mitochondria into the cytoplasm and the declined level of apoptosis in Sertoli‐germ cells induced by MC‐LR were observed after the addition of CsA. These results indicated that the apoptosis of the co‐cultured Sertoli‐germ cells induced by MC‐LR was mediated by the p53‐dependent pathway, with the involvement of the opening of mPTP. [ABSTRACT FROM AUTHOR]