Breast cancer is the most common malignancy observed in females. Histologically, breast cancer is a heterogeneous disease with different subtypes and pathology, treatment options and prognosis. 1 Bryan et al 2 for the first time in 2006 explicitly presented the definition of triple-negative breast cancers (TNBCs) based on the expression of oestrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2). Other studies using gene expression profiling were able to classify breast cancer into five subtypes. 3,4 To date, TNBC is used frequently as a standard procedure to classify breast cancer patients for clinical care. TNBC is similar to the basal-like subtype, which is characterized by negative ER, PR and HER2 expression, and is associated with aggressive histology, poor prognosis and unresponsiveness to the endocrine therapies. 5,6 Moreover, TNBC has been used as a surrogate marker for the basal-like breast cancer, and approximately 80-90% of TNBCs are basallike breast cancers.7 Younger females have a higher rate of basal or breast cancer susceptibility gene mutation-related TNBC, whereas older females have a higher proportion of apocrine, normal-like and rare subtypes of TNBC, including neuroendocrine TNBC.8 Because only fewer specific targeting therapies and molecular therapies (such as endocrine or target therapy) are available than for other subtypes of breast cancer, the standard treatment for TNBC includes surgery combined with adjuvant chemotherapy and radiotherapy, but clinical outcome is poor. 7,9 Thus, early detection of this subtype of breast cancer is vital to improve the survival of patients.Although TNBC has been studied extensively in clinical and pathological literature, there are few reports on the radiological characteristics of this subtype of breast cancer. To date, mammography is known to be a precise diagnostic technique with high sensitivity and specificity in the evaluation of breast lesions, and the current reference standard in breast cancer screening is mammography with the sensitivity to detect early-stage breast cancer. Therefore, this study evaluated the mammographic and clinicopathological
This article reports an experimental study on the friction and wear behavior of carbon strip sliding against copper contact wire under strong electric current utilizing a high-speed block-on-ring tester. The dynamic mechanism of electric arc generation was investigated. Scanning electron microscopy was used to observe morphology of worn surfaces of the carbon strips. The results show that arc discharge has a certain correlation with low-frequency vibration of the carbon strip. The arc discharge frequency and the average single arc discharge energy initially decrease and then tend to stable with increasing normal load at different speeds. The wear rate increases first and then decreases and has the minimum when the load is equal to 100 N especially. Moreover, the wear rate steadily increases with increase in arc discharge energy and is almost directly proportional to arc discharge energy. Arc erosion was a dominant wear mechanism occurred in carbon strip sliding against copper contact wire at a low load, accompanying with adhesive wear and material transferring. However, mechanical wear was a main wear mechanism at a high load. Severe arc erosion weakened the conductivity of the carbon strip.
For both environmental and economic consideration, the use of recycled glass fiber-reinforced flame retardant poly(butylene terephthalate) (RGFFRPBT) is of significant importance. In the study, the mechanical, thermal, rheological, and flame retardant properties of RGFFRPBT granulated by different extruders were evaluated. To explore the relationship between the screw structure and the properties of the extruded RGFFRPBT, the carboxyl content (CC), and intrinsic viscosity ([Formula: see text]) of the processed polymer and the average GF length ([Formula: see text]) were investigated. Increasing the shear force of the extruder caused both [Formula: see text] and [Formula: see text] to decrease, whereas the CC increase. Variations of these parameters had a different effect on the properties of the RGFFRPBT. Both of mechanical and thermal properties of extruded RGFFRPBT deteriorated with the increase of screw shear force, while the thermal flowability improved. Furthermore, all the extruded products were classified as V-0 with LOI of 32.2%, and passed the glow wire ignition temperature test (GWIT). The results confirmed that the degradation of properties of RGFFRPBT can be controlled by screw-type extrusion. RGFFRPBT granulated by a single screw extruder with 30 mm diameter and length to diameter ratio of 30 was found to produce material with properties meeting the requirements for electronic and electrical applications.
Benzyltetrahydropalmatine hydrochloride (BTHP) exhibited antiarrhythmic action in animal models. I. Electrophysiological effects of BTHP were investigated in various heart preparations. 1) BTHP markedly prolonged functional refractory period and inhibited adrenaline-induced automaticity. It decreased spontaneously beating rate of right atrium and abolished ouabain-induced delayed afterdepolarization and triggered activity of papillary muscle. 2) In standard microelectrode and contractility experiments BTHP concentration-dependently prolonged the action potential duration (APD) and effective refractory period (FRP) between 1-100 mumol/L; the force of contraction remained unchanged. 3) In voltage clamp experiments BTHP 1-100 mumol/L inhibited in dose-dependent manner the Ik with IC50 of 13 mumol/L and inhibited also Is at high concentration. 4) In monophasic action potential (MAP) of feline ventricle MAPD50 and MAPD90 were prolonged by BTHP in normal myocardium, and shortened APD induced by ischemia and reperfusion was restored to normal level. 5) In ECG and His-bundle electrogram heart rate was reduced; P-R and A-H interval were prolonged, but H-V interval and V duration were unaffected. II. BTHP showed a competitive alpha 1-adrenoceptor-blocking effect with pA2 value of 5.8 and 5.86 in rat anococcygeus muscle and rabbit aortic strips respectively. Radioligand binding assays showed that BTHP had affinity for both alpha 1 and alpha 2-adrenoceptor. The results from these experiments show that BTHP is a new K+ channel blocker of Chinese medicinal origin with alpha 1-adrenoceptor-blocking action.
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