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Developing public transportation and giving priority to buses is a feasible solution for improving the level of public transportation service, which facilitates congestion alleviation and prevention, and contributes to urban development and city sustainability. This paper presents a novel bus operation control strategy including both holding control and speed control to improve the level of service of transit systems within a connected vehicle environment. Most previous work focuses on optimization of signal timing to decrease the bus signal delay by assuming that holding control is not applied; the speed of buses is given as a constant input and the acceleration and deceleration processes of buses can be neglected. This paper explores the benefits of a bus operation control strategy to minimize the total cost, which includes bus signal delay, bus holding delay, bus travel delay, acceleration cost due to frequent stops and intense driving. A set of formulations are developed to explicitly capture the interaction between bus holding control and speed control. Experimental analysisand simulation tests have shown that the proposed integrated operational model outperforms the traditional control, speed control only, or holding control only strategies in terms of reducing the total cost of buses. The sensitivity analysis has further demonstrated the potential effectiveness of the proposed approach to be applied in a real-time bus operation control system under different levels of traffic demand, bus stop locations, and speed limits. [ABSTRACT FROM AUTHOR]

Previous studies reported discrepant white matter diffusivity in mild traumatic brain injury (mTBI) on the base of Glasgow Coma Scale, which are unreliable for some TBI severity indicators and the frequency of missing documentation in the medical record. In the present study, we adopted the Mayo classification system for TBI severity. In this system, them TBI is also divided into two groups as "probable and symptomatic" TBI. We aimed to investigate altered microstructural integrity in symptomatic acute TBI (<1 week) by using tract-based spatial statics (TBSS) approach. A total of 12 patients and 13 healthy volunteers were involved and underwent MRI scans including conventional scan, and SWI and DTI. All the patients had no visible lesions by using conventional and SWI neuroimaging techniques, while showing widespread declines in the fractional anisotropy (FA) of gray matter and white matter throughout the TBSS skeleton, particularly in the limbic-subcortical structures. By contrast, symptomatic TBI patients showed no significant enhanced changes in FA compared to the healthy controls. A better understanding of the acute changes occurring following symptomatic TBI may increase our understanding of neuroplasticity and continuing degenerative change, which, in turn, may facilitate advances in management and intervention. [ABSTRACT FROM AUTHOR]

Neonates are known to exhibit increased susceptibility to bacterial and viral infections and increasing evidence demonstrates that the increased susceptibility is related to their attenuated immune response to infections. The lung is equipped with an innate defense system involving both cellular and humoral mediators. The present study was performed to characterize the expression of inflammatory mediators in the lung of neonatal rats in comparison with older animals. Rats at postnatal day 1 (P1), P21, and P70 were treated with saline or 0.25 mg/kg lipopolysaccharide (LPS) via intraperitoneal injection. Two hours later, animals were sacrificed and the transcriptional response of key inflammatory mediators and enzyme activity of myeloperoxidase (MPO) in the lung of these animals were examined. LPS-induced messenger RNA (mRNA) expression of pro-inflammatory cytokines, namely interleukin (IL)-1β, IL-6, and tumor necrosis factor-α, anti-inflammatory cytokines, namely IL-10 and IL-1 receptor antagonist (IL-1ra), and chemokines, namely macrophage inflammatory protein (MIP)-1β, MIP-2, and monocyte chemotactic protein-1, in P1 lung was much reduced compared to that in P21 and P70 animals at 2 hours postinjection. These data suggest that LPS-induced transcriptional response of cytokines and chemokines was much reduced in P1 lung even though the protein levels of these genes were not ascertained and mRNA levels of these genes may not reflect their final protein levels. MPO activity in LPS-treated P1 lung was also significantly attenuated compared to that in LPS-treated P70 lung, suggesting impaired neutrophil infiltration in P1 lung at 2 hours following LPS treatment. In parallel, the baseline mRNA expression of LPS-binding protein (LBP) in P1 lung was much lower than that in P21 and P70 lungs. While the protein level of LBP was not examined and the mRNA level of LBP may not reflect its final protein level, the reduced transcriptional response of cytokines and chemokines in P1 lung at 2 hours following LPS treatment may be attributed to lower LBP expression in P1 lung as compared to P21 and P70 lungs. [ABSTRACT FROM AUTHOR]

(NaxKy) (Nb0.885Sb0.08)-0.035LiTaO3 lead-free piezoelectric ceramics (NxKyNS-LT) with an excessive amount of Na or K were synthesized by conventional solid-state processes. Effects of Na/K ratio on structure and electrical properties of NxKyNS-LT ceramics were investigated. Excessive Na or K did not change the major crystal structure and barely influenced the sintering temperature, but excessive Na or K exhibited effects on grain size. Better piezoelectric properties of the ceramics were achieved when a certain amount of excessive K was added (the Na/K ratio before calcining was adjusted to 0.520:0.450). X-Ray fluorescence was used to examine the cause, and the enhanced properties are attributed to the formation of an MPBlike composition when the Na/K was changed. Specimens with properties of d33=183 pC/N, kp=0.33, Qm=103 were obtained in this work. [ABSTRACT FROM AUTHOR]

The 0.95(K0.5Na0.5NbO3)-0.05Li(Nb0.5Sb0.5)O3 doped with 0.8 mol% copper oxide (CuO) lead-free piezoelectric ceramics were synthesized by conventional solid-state reaction route. The introduction of CuO could significantly improve the sinterability of 0.95(K0.5Na0.5NbO3)-0.05Li(Nb0.5Sb0.5)O3 ceramics. The grain size of the specimen was considerably decreased due to the formation of a large amount of liquid phase when the sintering temperature exceeded 960°C. The piezoelectric constant (d33), planar electromechanical coupling (kp), and dielectric constant (ε33T=ε0) values increased with increasing relative density and grain size. The improved piezoelectric and dielectric properties of d33 =207 pC/N, kp =44%, tan δ = 0.0137, Qm =320, and (ε33T=ε0 = 340 can be obtained for specimens sintered at 960°C for 2 h. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to characterize postnatal development of lipopolysaccharide (LPS)-induced inflammatory response in the brain. Methods: Postnatal day (P)1, P21 and P70 Sprague-Dawley rats were treated with saline or 0.25 mg/kg LPS for 2 h, and the mRNA expression of neuroinflammatory mediators in the brain was determined using reverse transcriptase-polymerase chain reaction (RT-PCR). The kinetics of LPS-induced neuroinflammatory mediators in the brain of P1 and P21 animals was determined using RT-PCR, and the kinetics of LPS-induced cytokines in the serum were determined using ELISA. The basal levels of Toll-like receptor (TLR)-4, CD14, and myeloid differentiation factor 88 (Myd88) were measured at the mRNA and protein levels using RT-PCR and Western blot assay respectively. Results: The mRNA expression levels of cytokines and chemokines were considerably increased in P21 and P70 brains but not significantly altered in P1 brain at 2 h following LPS stimulation. Instead, the induction of cytokines and chemokines was significantly delayed in the brain of P1 animals following LPS stimulation, which was associated with diminished Myd88 production in P1 brain. In parallel, the cytokine response in the serum of P1 animals after LPS stimulation was also delayed compared to P21 animals. Conclusions: TLR-4-mediated innate immunity in the brain was significantly delayed in P1 animals, and underwent significant development during the early postnatal period. [ABSTRACT FROM AUTHOR]

Lead-free 0.94(K0.48Na0.535)NbO3-0.06LiNbO3-xmol%CuO ceramics were synthesized by conventional ceramics processes. The doping of CuO can decrease the sintering temperature to 890°C and effectively promote the densification of 0.94(K0.48Na0.535)NbO3-0.06LiNbO3 ceramics. X-ray diffraction result reveals that doping of CuO induces lattice distortion. Homogeneous grain growth is observed, due to the presence of liquid phase that resulted from the addition of CuO. The ceramics sintered at 890°C show fairly good properties with the planar electromechanical coupling factor kp = 34.8%, piezoelectric constant d33 = 157.5 pC/N, dielectric constant ϵ33T/ϵ0 = 391, and mechanical quality factor Qm = 173.5. [ABSTRACT FROM AUTHOR]

Uniform magnetic Fe3O4chains with an average length of 20 μm built up by tens of self-assembled microspheres have been synthesized viaa simple surfactant-free hydrothermal method. A possible “nucleation-growth-connection-crystallization” growth mechanism has been proposed for the formation of the Fe3O4chains. [ABSTRACT FROM AUTHOR]

A general combined hydrothermal and annealing process for the fabrication of ferrite/perovskite oxide core/shell nanostructures was introduced. The coating of a perovskite oxide (ABO3) layer on spherical ferrite particles was performed in two steps. A dense and smooth amorphous layer containing B-site ions of the perovskite oxide was coated first viaa controlled hydrolysis and aging process. During hydrothermal treatment and subsequent annealing process, the A-site ions were incorporated in situinto the as-coated amorphous layer preserving the spherical morphology. This synthesis of ferrite/perovskite oxide core/shell nanostructures was demonstrated in systems like Fe3O4/PbTiO3, γ-Fe2O3/PbTiO3, γ-Fe2O3/Pb(Zr,Ti)O3, CoFe2O4/BaTiO3, CoFe2O4/PbTiO3and CoFe2O4/Pb(Zr,Ti)O3. This method allowed the shell thickness of the composite particles to be manipulated in a controlled manner with various core sizes. After the coating, the core and shell materials showed strong interactions and the ferroelectric layer dramatically affected the crystal structure, resistivity and magnetic properties of the composites. [ABSTRACT FROM AUTHOR]

Combustion synthesis of Ti3SiC2/TiC composites from 3Ti/ xSi/2C ( x=1, 1.1, 1.2) powders was conducted under high-gravity conditions with gravity up to 895 G. The results showed that the phase composition of the products strongly depended on the gravity level. We find that high-gravity synthesis favors the growth of TiC phase over Ti3SiC2 phase, as a consequence of the reduced existence time of the Ti–Si liquid phase. This discovery suggests that gravity provides a new leverage for controlling product phase composition in combustion synthesis. It was also found that the densification process during combustion synthesis could be enhanced under a high-gravity condition. [ABSTRACT FROM AUTHOR]

Plate-like Na0.5Bi0.5TiO3 (NBT) particles with perovskite structure were synthesized by topochemical microcrystal conversion from plate-like particles of layer-structured Na0.5Bi4.5Ti4O15 (NBIT) at 950°C in NaCl molten salt. As the precursors of NBT, plate-like NBIT particles were first synthesized by molten salt process by the reaction of Bi4Ti3O12, Na2CO3, and TiO2. After the topochemical reactions, layer-structured NBIT particles were transformed to the perovskite NBT platelets. NBT particles with a thickness of approximately 0.5 μm and a length of 10–15 μm retained the morphology feature of the precursor. High-aspect-ratio NBT platelets are suitable templates to obtain textured ceramics (especially NBT-based ceramics) by (reactive) template grain growth process. [ABSTRACT FROM AUTHOR]

The equilibrium compositions of a thermite reaction system (Fe2O3+Cr2O3+CrO3+NiO+O2+N2+TiO2+C+S+CaO+Al), which was used to prepare Ni-based alloys, were predicted by means of the free energy minimization method. The effects of the reactant contents on the equilibrium compositions and the adiabatic temperature of the thermite reaction system were analyzed. The microstructure of the Ni-based alloys was investigated. The thermodynamic analysis indicated that the products of the thermite reaction system contained primarily Al2O3, Fe, Ni, Cr, Ni3Al and NiAl, due to impurities C, N2 and S in the raw materials, there could also exist TiC, Cr7C3, CrN, CaS and TiN in the equilibrium products. The amount of Ni3Al and NiAl in the products increased with increase of the aluminum content in the starting materials. The microstructure investigation showed that the Ni-based alloys consisted of austenite, ferrite, Ni3Al and NiAl. The existence of Ni3Al and NiAl in the Ni-based alloys reconciled with the predictions of thermodynamic analysis, suggesting the free energy minimization method is useful in designing advanced materials with multiple components by thermite reaction technique. [ABSTRACT FROM AUTHOR]

This paper studies the formation of titanium nitride (TiN) by combustion of Ti particles in air. It is proposed that the combustion reaction is a dynamically controlled process, in which the formation of TiN is fulfilled by delayed gas infiltration behind the propagation of combustion wave. With the addition of NH4Cl or carbon black, the yield of TiN can be enhanced. The as-synthesized TiN grains show a terraced morphology with parallel layers stacked in the normal direction. It is thought that this terraced morphology has been derived from a surface-coarsening process. The parallel layers show regular hexagonal outlines and thus are considered to be (111) planes according to the symmetric characters of the FCC structure. The (111) texture is also revealed by X-ray diffraction results, where the relative intensity of (111) peak is clearly higher than the reference in the JCPDS card. In addition, nanoscale twinning areas are observed in TiN grains. From transmission electron microscopy (TEM) results, it is determined that the twinning plane is (111) and the twinning direction is [ 11]. The movement of atoms during twinning is discussed according to the FCC structure of TiN and high-resolution TEM images. [ABSTRACT FROM AUTHOR]

Barium strontium titanate is a promising material for microwave-phased array applications. 1,2 In this study, highly dense and fine-grained Ba0.6Sr0.4TiO3 ceramics were prepared using the spark plasma sintering (SPS) technique. The structure and dielectric tunable properties of the samples were investigated. The “distorted nano-region” emerged in the interior of the grains of SPS samples, and resulted in the deterioration of the dielectric tunable properties of Ba xSr1− xTiO3. This phenomenon indirectly testified to the assumption of the “polar nano-region” mechanism. After the SPS samples were annealed, the “distorted nano-region” disappeared and better dielectric tunable properties were obtained. The dielectric constant was decreased to 1048, and the K value (Commutation Quality Factor) reached 7089. [ABSTRACT FROM AUTHOR]

A high-aspect-ratio platelet sodium niobate (NaNbO3) was synthesized by a topochemical reaction. Plate-like layered-perovskite Bi2.5Na3.5Nb5O18 (BNN5) as a precursor was first prepared, and then Bi3+ in the precursor phase was replaced by Na+ through topotactic conversion and perovskite NaNbO3 formed at 950°C in NaCl molten salt. NaNbO3 crystals had an average length of 15 μm and a thickness of 0.5 μm. Scanning electron microscope and high-resolution transmission electron microscope analyses indicated that the retro-synthesis process of the desired perovskite NaNbO3 retained the morphological and structural features of the BNN5 precursor. It may be possible to synthesize other perovskite-structured templates using the same method. [ABSTRACT FROM AUTHOR]

A 3D mathematical model was developed to simulate the weld pool development in a moving A-TIG weld pool with different oxygen and sulfur concentrations. It is shown that the surface active elements—oxygen and sulfur, which change the temperature coefficient of surface tension from a negative value to a positive one, can cause significant changes in fluid flow patterns and the weld penetration. When surface active element content increases, the weld penetration and depth/width ratio increase sharply and then remain nearly a constant. Positive temperature coefficient of surface tension dominates the fluid flow and the weld pool is narrow and deep. The further increasing surface active element content leads to an inappreciable difference in the weld pool size and shape when the oxygen content increases beyond 280 ppm and sulfur content beyond 125 ppm. Positive and negative temperature coefficients of surface tension co-exist in the weld pool when surface active element content is less than the critical value. The fluid flows in the weld pool change apparently with different surface active element. Depending upon the oxygen and sulfur concentrations, three, one or two vortexes that have different positions, strength and directions may be found in the weld pool. The vortexes with opposite direction caused by positive temperature coefficient of surface tension can efficiently transfer the thermal energy from the arc, creating a deep weld pool. [ABSTRACT FROM AUTHOR]

Single-phase Yb α-SiAlON ceramics in-situ toughened by elongated grains were prepared by pressureless sintering, with the crystalline powder prepared by combustion synthesis used as seed crystals. The effects of seed addition on the densification, phase transformation, microstructure development, and mechanical properties of the samples were investigated in detail. From the experimental results, it was found that the added seed crystals could promote the phase transformation and facilitate the growth of elongated grains. By adding seed crystals the fracture toughness of the sintered α-SiAlON ceramics was considerably improved, with no obvious degradation in the bulk density and hardness at the same time. [ABSTRACT FROM AUTHOR]

Novel Y α-SiAlON whiskers with high aspect ratios were prepared by combustion synthesis, except for common isotropic grains. The growth process of whiskers was investigated, and experimental results showed that the predominant growth mode of whiskers was the vapor-liquid-solid (VLS) mechanism. In contrast to the usual situation, here the liquid phase played two roles during the growth of Y α-SiAlON whiskers; that is to say, in addition to acting as a medium for mass transportation, the liquid phase took part in reactions itself. It was also found that proper addition of Fe2O3 could facilitate the development of whiskers with no remarkable deterioration on the phase assemblage of combustion products. [ABSTRACT FROM AUTHOR]

In this paper, single-phase Yb α-SiAlON powder with rod-like crystals was fabricated by combustion synthesis. The microstructural development of the rod-like α-SiAlON crystals was studied, and anisotropic grain growth was observed. Furthermore, the growth mechanism of the rod-like α-SiAlON crystals was investigated, and the experimental results indicated that during the anisotropic grain growth, the fast growth plane was the basal plane in the hexagonal crystal lattice. [ABSTRACT FROM AUTHOR]

Samples in the MgO–Al2O3–SiO2 system were prepared by the sol–gel technique. The coalescence, sintering characteristics, and crystallization were investigated by X-ray diffraction, thermal analysis, and scanning electron microscopy. The dielectric properties and density were measured with an impedance analyzer. Results demonstrated that the obtained cordierite powders synthesized with the sol–gel method distribute uniformly and its effective size is 474 nm. The glass powder could be sintered at 950 °C, and the polymorphic modification cordierite detected in the sintered sample was only stable hexagonal α-phase. The sintering densification process was performed mainly in the temperature range from 800 °C to 930 °C, and follows the viscous floating principle. The dielectric constant of the sintered body is 4.2 and its dielectric loss is lower than 0.001 at high frequency (1.5 GHz). [ABSTRACT FROM AUTHOR]

Aluminium nitride (AlN) with various morphologies was fabricated through a sublimation-recrystallization method. The influences of type of reactor and temperature gradient were explored, as well as the orientations and growth mechanism of the obtained AlN whiskers. In the early stage of preparation, a vapour-liquid-solid (VLS) mechanism dominated, producing AlN pillars, whiskers and noncrystalline fibres. In the later stage, as the catalyst liquid was removed by volatilization, the pillars and noncrystalline fibres stopped growing, but the growth of AlN whiskers continued through a vapour-solid (VS) mechanism. By Laue method and rotating-crystal method of x-ray diffraction, together with electron diffraction, most of the AlN whiskers were discovered to grow on planes $$\left\{ {2\bar 1\bar 10} \right\},\left\{ {0001} \right\} $$ , or $$\left\{ {10\bar 1|} \right\} $$ , where l = 0, 1, 2, 3, along crystal axes $$\left\{ {2\bar 1\bar 10} \right\},\left\{ {0001} \right\}$$ , or $$\left[ {10\bar 1w} \right] $$ , where w = 0, 1, 2, 3. Oblique grown whiskers also appeared, with a growth direction at an angle of about 54° to the growth plane, $$\left\langle {10\bar 12} \right\rangle $$ . [ABSTRACT FROM AUTHOR]

Aluminum nitride (AIN) ceramics, with binary additives B2O3-Y2O3, were sintered at temperatures from 1700 to 1850 °C. The microstructure and sintering characteristics were studied by XRD, HREM, SEM and TEM/EDS, which showed that Y2O3 gave different yttrium aluminates through the reaction with Al2O3 under different conditions. With the increase of sintering temperature, the yttrium-to-aluminum atomic ratio Y/Al decreased in the secondary phases of the sintered bodies. It was discovered that B2O3 could dissolve in the yttrium aluminates, forming some ordered structure with a superlattice. After sintering at 1850 °C for 4 h, a specimen with a fine microstructure and a thermal conductivity of 190 W m−1 K−1 was obtained. [ABSTRACT FROM AUTHOR]

Aluminum nitride (AlN) fibres were synthesized by carbothermal reduction of aluminum silicate fibres and carbon black in a flowing nitrogen atmosphere. XRD and SEM were employed to study the phase structure, chemical composition and morphologies of the products. It is suggested that aluminum silicate fibres can be converted into AlN fibres by carbothermal reduction. SEM confirmed that the fibres maintained the morphologies of aluminum silicate fibres during reduction, but their details of surface have been altered. A carbothermal nitriding model of the aluminum silicate fibres has been developed. [ABSTRACT FROM AUTHOR]

Describes an experiment involving mammalian hepatocyte nuclear factor-3 (HNF-3) and the Drosophila homeotic gene fork head proteins. Isolation of HNF-3/fork head homolog-4 (HFH-4) by polymerase chain reaction amplification of rodent brain cDNA; Expression in the adult bronchiolar epithelium.

Textured 0.94Na0.5Bi0.5TiO3–0.06BaTiO3 (NBT–6BT) ceramics were fabricated by templated grain growth (TGG) using anisotropically shaped Na0.5Bi0.5TiO3 (NBT) templates. Platelet NBT was synthesized by the topochemical technique, using precursor Na0.5Bi4.5Ti4O15 (NBIT). The NBT particles have an average length of 10–15 μm and a thickness of 1 μm, which are suitable templates for obtaining textured ceramics (especially NBT-based ceramics) by the TGG process. This study revealed that the NBT templates are effective in inducing grain orientation in NBT–6BT ceramics. For NBT–6BT ceramics textured with 5 vol% NBT templates, a Lotgering factor of 0.87 and a d33 of 299 pC/N are given. [ABSTRACT FROM AUTHOR]

Novel faceted α-SiAlON micro-crystals were prepared by combustion synthesis with proper additives. These crystals exhibited various end shapes, including smooth flat hexagonal faces, pyramids bounded by six small isosceles triangles, and partial pyramids with the sharp roofs removed. The formation mechanisms of different crystal shapes were discussed, and a terraced epitaxial nucleation mode for α-SiAlON was proposed. By this nucleation mode, two interesting crystal morphologies were formed: a terraced tower structure and a T-like shape. Transmission electron microscopy results showed that the fast growth direction of rod-like α-SiAlON crystals was parallel to the c-axis. [ABSTRACT FROM AUTHOR]