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With rapid development of urban rail transit, maglev trains, benefiting from its comfortable, energy-saving and environmentally friendly merits, have gradually entered people's horizons. In this paper, aiming at improving the aerodynamic performance of an urban maglev train, the aerodynamic optimization design has been performed. An improved two-point infill criterion has been adopted to construct the cross-validated Kriging model. Meanwhile, the multi-objective genetic algorithm and complex three-dimensional geometric parametrization method have been used, to optimize the streamlined head of the train. Several optimal shapes have been obtained. Results reveal that the optimization strategy used in this paper is sufficiently accurate and time-efficient for the optimization of the urban maglev train, and can be applied in practical engineering. Compared to the prototype of the train, optimal shape benefits from higher lift of the leading car and smaller drag of the whole train. Sensitivity analysis reveals that the length and height of the streamlined head have a great influence on the aerodynamic performance of the train, and strong nonlinear relationships exist between these design variables and aerodynamic performance. The conclusions drawn in this study offer the chance to derive critical reference values for the optimization of the aerodynamic characteristics of urban maglev trains.

Dirac semimetals (DSMs) are classified into different phases based on the types of the Dirac fermions. Tuning the transition among different types of the Dirac fermions in one system remains challenging. Recently, KMgBi was predicted to be located at a critical state that various types of Dirac fermions can be induced owing to the existence of a flat band. Here, we carried out systematic studies on the electronic structure of KMgBi single crystal by combining angle-resolve photoemission spectroscopy (ARPES) and scanning tunneling microscopy/spectroscopy (STM/STS). The flat band was clearly observed near the Fermi level. We also revealed a small bandgap of ~ 20 meV between the flat band and the conduction band. These results demonstrate the critical state of KMgBi that transitions among various types of Dirac fermions can be tuned in one system., 15 pages, 4 figures

SUMMARY In recent years, there have been more and more reports about cystadenoma. Cystadenoma can occur in many parts of the body, and cystadenoma in different parts may show different clinical symptoms, however, some patients with cystadenoma have no symptoms. The vast majority of cystadenomas are benign lesions, but a small number of cystadenomas can be malignant. For example, a small number of ovarian cystadenomas and pancreatic cystadenomas may be malignant. This study reported a patient with small intestinal cystadenoma diagnosed by pathology. The patient's physical examination revealed a lesion in the left upper abdomen. He had only abdominal distension and no other discomfort. His laboratory examination results were basically normal, i.e. blood routine, urine routine, stool routine, liver function, kidney function, myocardial enzyme, tumor marker, etc. The patient underwent sectional small intestine resection and the pathological sample was analyzed. The histological findings of the resected intestinal sample were consistent with cystadenoma. Computed tomography scan of the abdomen was performed 4 months after the surgery. No recurrence of the tumor was found. The patient recovered in good condition. By consulting the literature, I found very few reports of small intestinal cystadenoma before, it was very rare. This article described the clinical manifestation, diagnosis and differential diagnosis, treatment and prognosis of a case of small intestinal cystadenoma, it suggested that cystadenoma can occur in the small intestine, other than the ovary, pancreas, liver, lung, thyroid, prostate, seminal vesicle, skin, etc. The cystadenoma in small intestine is easy to be mistaken with other tumors, such as small intestine stromal tumor, small intestine adenocarcinoma, small intestine lipoma, small intestine hemangiomas, etc., and it is difficult to fully confirm through imaging examinations, such as computed tomography and magnetic resonance imaging. Laparotomy and histopathological examination are necessary before definitive diagnosis. This disease can be treated by small bowel resection at the affected region and good prognosis can be achieved.

Oxaliplatin has shown good anti-tumour activity in the treatment of tumours involving the digestive system. However, its application is limited because of severe neurotoxicity in some patients. The purpose of this study was to evaluate whether compound porcine cerebroside and ganglioside (CPCG) can reduce or prevent oxaliplatin-induced neurotoxicity.Patients with digestive system tumour who received oxaliplatin-based chemotherapy were retrospectively divided into experimental and control groups according to the receipt of CPCG during chemotherapy. Adverse events at the end of each chemotherapy cycle were recorded. We compared the incidence of neurotoxicity between the two groups and graded the neurotoxicity symptoms using the Common Terminology Criteria for Adverse Events v5.0.The study included 115 patients (experimental group, 57; control group, 58). The number of chemotherapy cycles (6.65 vs. 6.41, p=0.540) and oxaliplatin dose (775.92 mg/m2 vs. 724.20 mg/m2, p=0.250) were comparable between the two groups. All patients developed grade 1 to 3 neurotoxicity; grade 4-5 neurotoxicity was not observed. The incidence of neurotoxicity and the probability of advanced neurotoxicity were significantly lower in the experimental group than in the control group (p0.05). After a 6 to 18 months follow-up, the two groups showed no significant differences in the chemotherapy response and recurrence rate (p=0.846).CPCG reduces oxaliplatin-induced neurotoxicity without reducing the efficacy of oxaliplatin-based regimens; thus, it can be used for preventing oxaliplatin-induced neurotoxicity in patients with cancer.

The extrudate swell ratios of polypropylene (PP) composite melts filled with graphene nano-platelets (GNPs) were measured using a capillary rheometer within a temperature range of 180–230 °C and apparent shear rate varying from 100 to 4000 s−1 in order to identify the effects of the filler content and test conditions on the melt die-swell behavior. It was found that the values of the extrudate swell ratio of the composites increased with increasing apparent shear rate, with the correlation between them obeying a power law relationship, while the values of the extrudate swell ratio decreased almost linearly with rise in temperature. The values of the melt extrudate swell ratio increased approximately linearly with increasing shear stress, and decreased roughly linearly with an increase of the GNP weight fraction. In addition, the extrudate swell mechanisms are discussed from the observation of the fracture surface of the extrudate using scanning electronic microscopy. This study provides a basis for further development of graphene reinforced polymer composites with desirable mechanical performance and good damage resistance.

A transmission electron microscope study has been made of a silicon nitride component with 6 w/o yttrium oxide as a sintering aid hot isostatically pressed (HIP) with an encapsulation glass of borosilicate. The TEM study concentrated on the interface region between ceramic and glass. Two different types of hexagonal boron nitride were formed near the interface. One, with a textured structure, seemed to nucleate heterogeneously on the surfaces of silicon oxynitride grains. The (001) planes of the crystals extended outwards, giving a thickness of approximately 0.5 microns. The other type formed as hexagonally shaped grains separate from the first type and appeared to have grown as several segments in different directions around a nucleus. In each segment BN layers are parallel to each other and perpendicular to their common [001]BM direction. This second type of BN crystal was also detected a little further from the surface within the silicon nitride. The volume fraction of additive glassy phase tended to be lower in this surface region than in the bulk. Possible mechanisms of prevention of encapsulation glass penetration into the porous ceramic component during HIP were discussed.

The objective of this work was to prepare for transmission electron microscopy (TEM) a layered structure of materials with fragile microstructure. The samples consisted of two layers of different materials, silicon nitride and borosilicate glass, loosely bonded together. The low strength of the sample resulted in fragmentation during more conventional preparation. However, it was possible to prepare the fragments by mounting them in a titanium specimen carrier with aluminium strips as support. After grinding and polishing, a technique of low-angle ion milling was used to obtain electron beam transparent areas at the nitride/glass interface.

The solidification path and phase constituents of alloys in the magnesium-rich corner of the Mg–Zn–misch metal (MM) pseudo-ternary system have been investigated by a combination of differential thermal analysis, analytical electron microscopy and X-ray diffraction. The solidification behaviour diagram for this system was found to be dominated by a large two-phase (α-Mg plus T-phase) field in which the lowest eutectic temperature was ∼500°C. T-phase has a c-centred orthorhombic crystal structure and exhibits a wide range of stoichiometry. The interdendritic eutectic phase in the pseudo-binary Mg–MM system is Mg12MM which has the same b c t structure as Mg12Ce. The eutectic temperature here is 593°C.

The microstructures and age hardening behaviours of a series of Mg-Al-rare earth (RE) alloys that had been either pressure die cast or permanent mould cast were investigated by SEM and analytical TEM. Two types of phases, AlMM and AlMg, were found in the as cast alloys and no pseudoternary Mg-Al-RE phases were present. The AlMM phase was thermally stable during solution treatment at temperatures as high as 500°C, whereas AlMg partially dissolved in the α-Mg matrix during solution treatment at 420°C. No rare earth containing precipitates formed during heat treatment of the investigated alloys but two types of AlMg precipitation took place. Colonies of discontinuous precipitation containing alternate lamellae of α-Mg and AlMg formed preferentially in regions of α-Mg with high aluminium content. Spheroidisation and coarsening of the discontinuous precipitates occurred after aging at 200°C. Continuous precipitation of AlMg also occurred and these precipitates had a rodlike morphology and grew in preferred crystallographic directions. MST/3382

Crystal symmetry of the pseudo-ternary T-phases in Mg-Zn-rare earth alloys was observed. The convergent beam electron diffraction combined with selected area electron diffraction (SAED) determined the point group and space group for this phase. The phase was formed interdendritically during the solidification of the alloys. Extensive SAED detected a C-centered orthorhombic crystal structure of the phase. The space group for T-phase is Cmcm

The precipitation sequence responsible for the age-hardening behaviour of a cast Mg-1.3 wt% rare-earth alloy has been investigated by analytical electron microscopy. Very fine intermediate precipitates formed at an early stage of ageing. Plate-shaped Mg3MM β′ precipitates (MM = misch metal) and hexagonal prism-shaped Mg12MM β precipitates were primarily responsible for age hardening. Precipitate morphologies, crystal structures and crystallographic orientation relationship were determined for the various types of precipitates that formed during ageing at different temperatures.

The solidification path and microstructure of cast Mg-9Zn and Mg-8Zn-1.5MM (misch metal) alloys have been investigated by a combination of thermal analysis and analytical electron microscopy. The addition of 1.5 wt pct MM had a strong influence on the as-cast microstructure with the introduction of new ternary interdendritic phases and structural modification of known binary phases. The temperature ranges for formation of these phases from the melt were identified, their crystal structures determined, and their compositions analyzed. Products from eutectoidal decomposition of the interdendritic phase in the binary Mg-9Zn alloy were also identified.

The age-hardening response of two cast Mg-Zn-RE alloys has been investigated and compared with that of a binary Mg-Zn alloy. The microstructures of the aged specimens were examined by analytical electron microscopy. Formation of a fine dispersion of rodlikeβ1′ precipitates is the main cause for age hardening, while extensive precipitation of disc-shapedβ2′ coincides with the onset of overaging. Rare earth additions retard the formation ofβ2′ precipitates and thus postpone overaging. Four different orientation relationships betweenβ2′ precipitates and matrix were found and explained in terms of the near-CSL model.

Diffusion bonding by hot isostatic pressing (HIP) was performed between Incoloy 909 and five different ceramics. Two of the ceramics were composites made from powder mixtures of Si3N4 and either 60 vol% TiN or 50 vol% TiB2, while three were monolithic materials, namely Si3N4 with 2.5 wt% Y2O3 as a sintering additive, Si3N4 without additives, and Si2 N2O without additives. A diffusion couple geometry was developed to facilitate the preparation of thin-foil specimens for examination by analytical electron microscopy (AEM). Diffusion bonding was performed by HIP at 927°C (1200K) and 200 MPa for 4 h. The formation of reaction layers was very limited, being less than 1 μm in total layer thickness. Two reaction products were found by AEM; a continuous, very thin, (⩽100 nm) layer of fine TiN crystals at the initial ceramic/metal interface, and larger grains extending about 100–500 nm into the superalloy and forming a semi-continuous layer of a G-phase suicide containing mainly nickel, silicon and niobium.

The N-nitroso derivative of an extensively used insecticide, propoxur, consistently induced dose-responsive chromosome aberrations and sister-chromatid exchanges (SCEs) in Chinese hamster ovary (CHO-W8) cells. Further investigations indicated that post-treatment incubation with a regular 1.5-cell-cycle period did not offer an unbiased estimation of the genotoxicity of N-nitroso carbamate insecticides. The scale of chromosome aberration induction increased with extension of the post-treatment incubation period. Comparable phenomena were not found in CHO-AGT cells proficient for O(6)-methylguanine-DNA-methyltransferase. In CHO-W8 cells, pulsed-treatment of the insecticide in the 1st replication cycle showed higher SCE induction than in the 2nd cycle. Similar phenomenon was also found in SCE induced by N-nitroso derivatives from other carbamate insecticides including aldicarb, carbofuran and methomyl. Treated cells did not show significantly perturbed cell cycle progression until 12 h after treatment removal. Based on the above observations, the O(6)-methylguanine-DNA adduct is suggested to be the major lesion caused by the delayed genotoxic effect of N-methyl carbamate insecticides as described in this report.

The objective of this work was to prepare for transmission electron microscopy (TEM) a layered structure of materials with fragile microstructure. The samples consisted of two layers of different materials, silicon nitride and borosilicate glass, loosely bonded together. The low strength of the sample resulted in fragmentation during more conventional preparation. However, it was possible to prepare the fragments by mounting them in a titanium specimen carrier with aluminium strips as support. After grinding and polishing, a technique of low-angle ion milling was used to obtain electron beam transparent areas at the nitride/glass interface.

This paper summarizes methods conventionally used to prepare thin foil samples of powder materials for transmission electron microscopy (TEM) and introduces another variant, ultramicrotomy, for the preparation of TEM samples of industrial dust powder. The choice of ultramicrotoming in the present work was based on two features of this technique: (1) it can produce thin-sectioned specimens with a uniform thickness; (2) it can retain the original elemental distribution in phases of the sample during sectioning. Dust powder preparation and the sectioning procedure are described in this paper. The results of the method are illustrated by examples of TEM/STEM micrographs of industrial dust.

Three carbamate insecticides (propoxur, methomyl, and aldicarb) were evaluated for their ability to induce micronuclei (MN) in vitro using cultured Chinese hamster ovary (CHO) cells, and in vivo in mouse bone marrow erythrocytes. In vitro, all three insecticides induced a significant increase in micronucleated binucleate cells, which was generally both dose and sample time dependent. The in vivo studies involved treating male BALB/c mice by different routes, either once or on 3 consecutive days, followed by multiple or single sampling. Treatment by intraperitoneal injection or oral gavage induced a significant increase in micronucleated reticulocytes (MNRETs) in peripheral blood. For all three chemicals, the MN response depended on sample time and the number of treatments, while for aldicarb, the response depended also on the route of exposure. These positive results demonstrate that propoxur, methomyl, and aldicarb are capable of inducing structural and/or numerical chromosomal aberrations in mammalian cells either in vitro or in vivo. Furthermore, based on the results obtained, on optimal in vivo MN protocol for carbamate insecticides is a single treatment followed by blood sampling at 24 and 48 hr after treatment.

The interaction of intense laser radiation with a metal surface in vacuum is a complicated process which involves surface melting, vaporisation, plasma formation, plasma heating and finally a breakdown or explosion of the superheated plasma. The explosion of the plasma causes a high-pressure shock wave, which acts as an impact on the material. The generated stress wave propagates and is absorbed in the material, causing elastic and plastic deformation, formation of dislocations, slip bands or other microstructural changes. Of the materials tested, an austenitic Hadfield manganese-alloyed steel was found to have the strongest tendency for a martensitic phase transformation, induced only by plastic deformation. An Iodine photo-dissociation laser [1] emitting at the wavelength of 1.315 µm was used for the experiments. The pulse duration was typically 1 ns and the pulse energy could be varied between 1–15 Joules.

The interaction of intense laser radiation with a metal surface in vacuum is a complicated process which involves surface melting, vaporisation, plasma formation, plasma heating and finally a breakdown or explosion of the superheated plasma. The explosion of the plasma causes a high-pressure shock wave, which acts as an impact on the material.The interaction of intense laser radiation with a metal surface in vacuum is a complicated process which involves surface melting, vaporisation, plasma formation, plasma heating and finally a breakdown or explosion of the superheated plasma. The explosion of the plasma causes a high-pressure shock wave, which acts as an impact on the material.

If a short laser pulse with high intensity is focussed on the surface of a target in vacuum, it will cause a nearly instantenuous vaporization of a limited volume of material. The rapid expansion of this material vapor produces an impact (=recoil) at the surface, similar to a blast or shock wave. The shock wave propagates and is absorbed in the material, causing microstructural changes.If a short laser pulse with high intensity is focussed on the surface of a target in vacuum, it will cause a nearly instantenuous vaporization of a limited volume of material. The rapid expansion of this material vapor produces an impact (=recoil) at the surface, similar to a blast or shock wave. The shock wave propagates and is absorbed in the material, causing microstructural changes.

Comparison of the two SAED patterns (Fig.l) obtained from Laves phase in Mg-9Zn and Mg- 8Zn-1.5RE (RE: rare earth additions made by adding misch metal), shows that the small amount of rare earth additions has a considerble influence on the crystal structure of this phase. The diffraction features suggest that the crystal structure of the Laves phase in the Mg-Zn-RE alloy is modulated by planar translation interfaces which are equivalent to a uniform sequence of antiphase boundaries (APBs) in a long period superstructure. From the splitting distance of the superlattice spots as illustrated in the schematic diagram in Fig. 1(c), the mean half period, which is measured in units of (100) interplanar spacings, is M ≈ 4.86. As shown by Van Dyck et al. the superstructure reflections (or the satellites of the basic spots) of a periodic APB structure are peaked at positions given by: g' = g - (1/d)(m - g.R)

Solid-fluid reactions often involve two or more simultaneous reactions because either the feed contains multiple fluid reactants or the fluid products are reactive with the solid. Three types of simultaneous reactions, independent, parallel, and consecutive, are examined in terms of the selectivity and the effectiveness factor based on the unreacted core shrinking model under isothermal conditions. Criteria for high selectivities are derived, and effects of diffusion and chemical reaction are discussed.

Based on the considerations of surface charge and surface recombination (or ion binding), the capacitances of the diffused double layer and the polar region are calculated as functions of ionic strength, pH value and external bias. Electrical capacitances of thin lipid films were measured under various conditions. In all cases, the change in capacitance is not more than 5%. Agreement between theory and experiment is fairly good except for the capacitance-voltage relation. It is concluded that though the magnitude of the observed membrane capacitance is determined by the center hydrocarbon region, its constancy and stability are attributed to the largeness and guarding action of the interface capacitances.

Currents through thin lipid films were measured versus temperature, applied voltage, pH value, ionic strength and ionic species. All experimental data tend to fit a two-component current theory, that is, the film current composed of a surface barrier jumping current and a surface recombination current. A good agreement was obtained in surface barrier height between theory and experiment. Breakdown phenomenon was observed and is interpreted as possibly arising from avalanche multiplication of ions, most probably from surface traps.

The kinetics of simultaneous, noncatalytic solid-gas reaction systems has been analyzed in terms of the selectivity and effectiveness factor, based on the unreacted core shrinking model. The reaction systems discussed include the first-order independent, parallel, and consecutive reactions with the simultaneous influences of heat and mass transfer. The effects of various chemical and transport properties on the stability, selectivity, and effectiveness factor of the system are discussed. The pseudosteady state approximation is employed to reduce the mathematical difficulties.

An electronic diagnoser of the arterial pulse has been designed to give three outputs: (1) pulse amplitude, (2) instantaneous pulse rate (IPR) and (3) spectral energy ratios (SER) at 5 and 10 Hz. The information thus provided will be useful for diagnosing many kinds of disease in the human body.

We demonstrated a hollow-core photonic crystal fiber as an absorption cell to observe the third harmonic derivative signal for laser frequency stabilization to P(9) line of the acetylene ν1+ ν3 overtone band.