Modelling and Analysis of Expansion Joints' Effect on Dynamic Performance of Railway Rigid Overhead System.

This study focuses on developing a comprehensive model of a rigid overhead system, which includes essential components such as the suspension structure, positioning clamp, and expansion joint. The modelling approach utilizes finite element theory and beam elements to accurately represent the displacement, stiffness, and mass characteristics of the system. The models also incorporate the suspension structure and positioning line clamp, which play crucial roles in suspending and positioning the busbar. Various suspension structures and positioning line clamps are evaluated based on their dynamic characteristics. The expansion joint, responsible for connecting different anchor sections of the rigid overhead system, undergoes a detailed analysis. Different assembly scenarios, including ideal and deflected assembly conditions, are considered. To simulate the dynamic behaviour of the expansion joint, additional beams are introduced into the system model. The primary finding of the analysis is that the maximum stresses observed in the constructed expansion joint model, under different temperature conditions and normal/deflected assembly conditions, remain within the permissible stress limits of the material. This indicates a high level of safety. However, certain areas exhibit stress concentration, particularly at the sliding block B and sliding rod A positions. This stress concentration is primarily attributed to the unique assembly form of the expansion joint. To improve stress distribution and enhance service reliability, the analysis suggests optimizing the installation deflection angle and geometric design of the expansion joint. Furthermore, the concentrated mass at the expansion joint significantly impacts the current collection quality of the pantograph-overhead system. Mitigating this negative impact can be achieved by reducing the mass of the expansion joint.

Microwave-Induced Deep Catalytic Oxidation of NO Using Molecular-Sieve-Supported Oxygen-Vacancy-Enriched Fe-Mn Bimetal Oxides.

A novel microwave (MW) catalytic oxidation denitrification method was developed, which can deeply oxidize NO into nitrate/nitrite with little NO2 yield. A molecular-sieve-supported oxygen-vacancy-enriched Fe2O3-MnO2 catalyst (Ov-Fe-Mn@MOS) was fabricated. Physicochemical properties of the catalyst were revealed by various characterization methods. MW irradiation was superior to the conventional heating method in NO oxidation (90.5 vs 70.6%), and MW empowered the catalyst with excellent low-temperature activity (100-200 °C) and good resistance to H2O and SO2. Ion chromatography analysis demonstrated that the amount of nitrate/nitrite accounted for over 90.0% of the N products, but the main product gradually varied from nitrate to nitrite as the reaction proceeded because of the switching of the main reaction path of NO removal. Mechanism analyses clarified that NO oxidation was a non-radical catalytic reaction: (i) the chemisorbed NO on ≡Mn(IV) reacted with O2* to produce nitrate and (ii) the excited NO* due to MW irradiation reacted with the active O* generated from Ov···O2 to form nitrite. Density functional theory calculations combined with electron paramagnetic resonance tests revealed the promotional effects of Fe2O3 in (i) boosting the Ov's quantity; (ii) facilitating O2 adsorption; (iii) increasing the nitrite formation; and (iv) alleviating the suppression of SO2.

Novel TNC-PDGFD fusion in fibrosarcomatous dermatofibrosarcoma protuberans: a case report.

BACKGROUND: Dermatofibrosarcoma protuberans (DFSP) is a superficial fibroblastic tumor characterized by high rate of local recurrence and low metastatic potential. Fibrosarcomatous transformation can rarely arise in DFSP either de novo or as recurrent, which represents a form of tumor progression and carries an increased risk of metastasis over classic DFSP. Cytogenetically, DFSP is characterized by a recurrent unbalanced chromosome translocation t (17;22)(q22;q13), leading to the formation of COL1A1-PDGFB fusion transcript that is present in more than 90% of cases. Alternative fusions involving the PDGFD with partners of COL6A3 or EMILIN2 have recently been documented in less than 2% of cases. Herein, we report a DFSP with fibrosarcomtous morphology harboring a novel TNC-PDGFD fusion. CASE PRESENTATION: A 54-year-old female presented with a slowly growing mass in the right thigh. Excision demonstrated a 2-cm ovoid, well-circumscribed, gray-white, mass. Microscopic examination revealed a partially encapsulated subcutaneous nodule without dermal connection. The neoplasm was composed of cellular and fairly uniform spindle cells with brisk mitoses, arranged in elongated fascicles and herringbone patterns, with focal collagenized stroma. The neoplastic cells were positive for CD34 and smooth muscle actin. Fluorescence in-situ hybridization analyses showed negative for COL1A1-PDGFB fusion as well as NTRK1/2/3 rearrangements. A subsequent RNA sequencing detected an in-frame fusion between exon 15 of TNC and exon 6 of PDGFD. This fusion was further confirmed by nested reverse transcription polymerase chain reaction amplification followed by Sanger sequencing. A diagnosis of fibrosarcomatous DFSP was rendered and the patient was in good status at a follow-up of 12 months after the operation. CONCLUSIONS: We report a fibrosarcomatous DFSP with novel TNC-PDGFD fusion, which adds to the pathologic and genetic spectrum of PDGFD-rearranged DFSP.

Caudatan A, an undescribed human kidney-type glutaminase inhibitor with tetracyclic flavan from Ohwia caudata.

Human kidney-type glutaminase (KGA) is an important target that is often over expressed in many cancer cells but very few effective inhibitors of this enzyme have yet reached clinical trials. Caudatan A and caudatan B, two undescribed tetracyclic flavans with an unusual ether bond between the C-4 and C-2' were isolated from the roots of Ohwia caudata (Thunb.) H.Ohashi. Caudatan A exhibited stronger inhibitory activity and caudatan B showed moderate effect from the results of inhibitory activities evaluations on KGA. The molecular docking and primary structure-activity relationship analysis revealed that the less steric hindrance at ring A was necessary to the effect. Therefore, combined its better solubility than that of bis-2-(5-phenylacetimido-1,2,4-thiadiazol-2-yl)ethyl sulfide (BPTES), caudatan A might be the potential candidate as the inhibitor of KGA for further studies.

Xanthoceraside hollow gold nanoparticles, green pharmaceutics preparation for poorly water-soluble natural anti-AD medicine.

In order to increase the solubility of poorly water-soluble natural product, xanthoceraside, an effective anti-AD compound from Xanthoceras sorbifolia Bunge, and maintain its natural property, the xanthoceraside hollow gold nanoparticles were successively prepared by green ultrasonic method with silica spheres as templates and HF solution as selective etching solvent. Hollow gold nanoparticles and drug-loaded hollow gold nanoparticles were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The solubilities of xanthoceraside loaded on hollow gold nanoparticles were increased obviously from 3.0µg/ml and 2.5µg/ml to 12.7µg/ml and 10.7µg/ml at 25°C and 37°C, respectively. The results of XRD and DSC indicated that the reason for this increase was mainly due to the amorphous state of xanthoceraside loaded on the hollow gold nanoparticles. In summary, the method of loading xanthoceraside onto hollow gold nanoparticles was a green and useful strategy to improve the solubility and dissolution of poorly water-soluble natural products and worth to applying to other natural products.

Cytotoxic and antioxidant constituents from the leaves of Psidium guajava.

Psidium guajava (Myrtaceae) is an evergreen shrub growing extensively throughout the tropical and subtropical areas. Four new compounds, guavinoside C, D, E and F (1-3, 10) were isolated from the leaves of P. guajava, along with six known ones (4-9). Their structures were elucidated by spectroscopic analysis. Compounds 1, 4 and 10 showed significant cytotoxic activities on HeLa, SGC-7901 and A549 cell lines, respectively. Compounds 1 and 4-10 showed antioxidant activities in DPPH, ABTS and FRAP assays, and five of them (1, 4-6, 10) exhibited stronger activities than that of vitamin C.