工程造价专业实训课程“二化结合”教学模式的实践研究

针对工程造价专业校内实训室建设停留在机房或依附建工专业实训室的弊端,创新实训室建设,提出"二化结合"实训室再造育人教学模式,以工作流程方式构建专业实训室,通过"软化"形式呈现的专业理论与实训知识和"硬化"形式呈现的实验实训室二者融合,使高职和五年制造价专业学生的核心课程有针对性和系统性的实训锻炼。实现理论知识学习与实践能力培养、学生校内实训与真实工作场景的紧密结合。

Effect of Ni-coated MoS2 on microstructure and tribological properties of(Cu−10Sn)-based composites

The(Cu−10Sn)−Ni−MoS2 composites,prepared by powder metallurgy,were studied for the effects of Ni-coated MoS2 on the microstructure,mechanical properties and lubricating properties.The mechanism of effects of Ni and MoS2 on the properties of composites was analyzed through a comparative experiment by adding Ni and MoS2 separately.The results show that the nickel wrapping around the MoS2 particles decreases the reaction rate of MoS2 with the copper matrix,and greatly improves the bonding of the matrix.The composites with 12 wt.%Ni-coated MoS2(C12)show the optimum performance including the mechanical properties and tribological behaviors.Under oil lubrication conditions,the friction coefficient is 0.0075 with a pressure of 8 MPa and a linear velocity of 0.25 m/s.The average dry friction coefficient,sliding against 40Cr steel disc,is measured to be 0.1769 when the linear velocity and pressure are 0.25 m/s and 4 MPa,respectively.

Synthesis and Crystal Structure of β-Diketiminate Ytterbium Dichloride

The reaction of anhydrous YbCl3 with lithium b-diketiminate, LLi (L = N,N- diphenyl-2,4-pentanediimine anion), in 1:1 molar ratio in THF gave rise to the title complex LYbCl2(THF)2 1 which has been characterized by single-crystal X-ray diffraction. It crystallizes in the orthorhombic system, space group Pna21(#33) with a = 19.657(8), b = 9.581(4), c = 14.107(6) ? V = 2656.8(18) 3, Z = 4, C25H33N2O2Cl2Yb, Mr = 637.49, Dc = 1.594 g/cm3, F(000) = 1268.00 and m(MoKa) = 3.744mm-1. The final R and wR are 0.031 and 0.073 for 2596 observed reflections with I > 2s(I), respectively. The X-ray crystal structure analysis revealed that the center ytterbium(III) is bonded to two chloride anions, two oxygen atoms from two tetrahydrofuran molecules and one chelate ligand b-diketiminate to form a six-coordinate distorted octahedral geometry.

Synthesis and Crystal Structure of Ethyl 4-(3,4-Methylenedioxylphenyl)-6-methyl-2-oxo-l,2,3,4-tetrahydropyridine-5-carboxylate under Microwave Irradiation

The crystal structure of the title compound (C16H17NO5) has been determined by single-crystal X-ray diffraction. The crystal is of monoclinic, space group C2/c with a = 18.520(2), b = 7.8910(1), c = 21.728(3) A, β = 104.77(1)°, V= 3070.4(7) A3, Mr= 303.31, Z = 8, Dc= 1.312 g/cm3, λ = 0.71073 A,μ(MoKα) = 0.098 mm-1 and F(000) = 1280. The structure was refined to R = 0.0486 and wR = 0.1287. There exist intermolecular hydrogen bonds in the crystal.

Synthesis and Crystal Structure of Pd(AETYF)Cl_2CH_2Cl_2 [AETYF = 4'5'Diaza-9' (4,5-bis(ethylthio)-1,3-dithiole-2-ylidene)-fluorene]

A stable Pd(II) compound Pd(AETYF)Cl2CH2Cl2 (AETYF = 4?5?diaza-9? (4,5-bis(ethylthio)-1,3-dithiole-2-ylidene)-fluorene) has been synthesized and its crystal structure was determined by X-ray crystallography. The crystal is of monoclinic, space group P21/c with a = 15.249(6), b = 8.619(3), c = 19.078(7) ? b = 106.932(8), C19H18Cl4N2PdS4, Mr = 650.79, V = 2398.6(16) 3, Z = 4, Dc = 1.802 g/cm3, F(000) = 1296, m = 1.579 mm-1, Npar = 268, the final R = 0.0538 and wR = 0.1282 for 5068 observed reflections with I > 2s(I). The crystal structure determi- nation shows that the atoms of the molecule, except two ethyl-groups, are conjugated in a quasi- plane and these molecules are further stacked or contacted via plane to plane or edge to edge p-p interactions, forming parallel molecular chains along the b axis.

Freezing Desalination

The solidification of a binary mixture causes allowed thermosolutal convection. Under certain conditions, the separation of its components gives rise to a preferential movement of migration of solutes. The quantity and the concentration of the obtained products depend on the mechanisms of sepa＇,ration which depend on different parameters and the applied boundary conditions. In this way, the freezing of H20-NaC1 mixture makes it possible to obtain a liquid phase which is charged in solute and is called brine and a solid phase which is composed of ice being able to become fresh water, and so it can works as a desalination process. In this paper, a series of experiments of seawater freezing on cold surface is carried out at the laboratory under different operating conditions. During these experiments, the role of each parameter （temperature of crystallization, duration of crystallizat on...） which is able to impact the final composition is focused on. After a preliminary series of experiment, the yield is： improved to reach rates of salt and make it possible to regard the water produced as drinkable according to the standards of WHO （World Health Organization）.

Structure - Antimicrobial Activity Relationship Investigation of Some Butadiene and Chalcone Derivatives

The biological activity against Staphylococcus aureus, and Eschericia coil were investigated implementing three series, the first series was l-phenyl-2-（4＇-X-phenyl）-4-（2,4-dichlorophenyl）-1,3-butadiene, where X = H, CH3, OCH3, NH2, C1, F, NO2 and COOEt; the second was 3,4-dichlorochalcone series namely 3-（3,4-dichlorophenyl）-l-（4＇-X-phenyl）-2-propen-l-one, where X = H, CH3, OCH3, NH2, CI, F, NO2 and CN; and the third one was 2,4-dichlorochalcone series namely 3-（2,4-dichlorophenyl）-l- （4＇-X-phenyl）-2-propen-l-one, where X = H, CH3, OCH3, NH2, C1, F, NO2 and COOEt. MIC, MBC and the percentage of inhibition （activity） at 20 ~tg/mL, 15 μg/mL and 10μg/mL against Eschericia coli, and at 7.5 lag/mL, 5 μg/mL and 2.5 μg/mL against Staphylococcus aureus, were determined for each compound in the three series. Highest MIC activity against E. coli and S. aureus were given by 2,4-dichlorochalcone series. Butadiene series was similar in behavior to 2,4-dichlorochalcone series in MIC activity against S. aureus. Results of MBC revealed that compounds in the three series exerted high activity against both types of bacteria. Compounds substituted with nitro or nitril exhibited higher activity than other compounds in the three series. Percentage of inhibition of halogenated compounds （4＇-C1 and 4＇-F） was almost equal in every series. Compounds with substituents （4＇-H and 4＇-CH3） showed fluctuation in activity according to the nature of each series.

Composite CoFe2O4/Bi3.1La0.9Ti3O12 Structures with Multiferroic Properties

Chemical solution route was used to synthesize Bi3.1La0.9Ti3O12 and CoFe2O4. Alternate CoFe2O4/Bi3.1La0.9Ti3O12 layers were deposited on Pt substrate （Pt/TiO2/SiO2/Si） by spin coating. X-ray diffraction and SEM （scanning electron microscopy） studies show composite-like polycrystalline films. Films were studied for leakage current, dielectric response, ferroelectric and ferromagnetic properties. Leakage current was low （〈 10^-8 A） in electric field below 120 kV/cm, and the dielectric response shows relaxation. Dielectric loss （tan 8） reduces 〈 3% at 10^6 Hz. Two and four layer structures showed room temperature FE （ferroelectric） and FM （ferromagnetic） responses with FE Pr （polarization） 〉 25℃/cm2 and ferromagnetic Mr （memory） 〉 52 emu/cm3. Co-existence of FE and FM can be attributed to stress due to different crystal structures of the material involved in composite film structure.

Synthesis and Structure Characterization of [HgCl(η~5-C_5H_3C(CH_3)=N-3- C_5H_4N)Fe(η~5-C_5H_5)]·(1/2)CH_2Cl_2

S A new cyclomercurated ferrocenylketimine containing pyridyl ring ([HgCl(5- C5H3C(CH3)=N-3-C5H4N)Fe(5-C5H5)]紺H2Cl2, Mr = 581.66) was synthesized and its molecular structure has been confirmed by IR, elemental analysis, 1H-NMR and X-ray crystal structure analysis. It is of monoclinic system, space group P21/c with a = 9.213(2), b = 17.479(4), c = 11.510(2) ? b = 100.32(3)o, V = 1823.7(6) 3, Z = 4, C17.5H16Cl2FeHgN2, Dc = 2.119 g/cm3, m = 9.497 mm-1, F(000) = 1100, R = 0.0436 and wR = 0.0987. The independent reflections are 3527, of which 3153 with I ≥ 2s(I) were observed. The compound contains a five-membered metallocycle. The mercury atom is bonded with the 2-position of substituted cyclopentadienyl ring (Cp), and coordinated weakly to the N atom of imino group. The pyridyl ring is almost perpendicular to the substituted Cp which is nearly coplanar with the metallocycle. The Hg(1)C(1) and Hg(1)Cl(1) bond lengths are 2.050(8) and 2.321(2) ? respectively.

Two-dimensional polymeric carbon nitride: structural engineering for optimizing photocatalysis

As a two-dimensional(2D) material, polymeric carbon nitride(g-C_3N_4) nanosheet holds great potentials in environmental purification and solar energy conversion. In this review, we summarized latest progress in the optimization of photocatalytic performance in 2D g-C_3N_4. Some of the latest structural engineering methods were summed up, where the relevant influences on the behaviors of photoinduced species were emphasized. Furthermore, the construction strategies for band structure modulation and charge separation promotion were then discussed in detail. A brief discussion on the opportunity and challenge of 2D g-C_3N_4-based photocatalysis are presented as the conclusion of this review.

A strategic study towards constructing the nine-membered azonane ring system of palhinine A via an azidoketol fragmentation reaction

A proposed strategy for constructing the nine-membered azonane ring system embedded in the isotwistane framework of palhinine A has been preliminarily studied on the basis of an azidoketol fragmentation reaction together with a SmI2-mediated pinacol coupling. Albeit negative results for building the azonane ring scaffold via a tertiary azidoketol fragmentation, the present exploration strategically provided an endeavor to probe the synthetically challenging issue in the synthetic study of palhinine A.

IC5, a dithiocarbamate derivative, inhibits colon cancer cell proliferation in vitro and colitis-associated colorectal carcinogenesis in vivo

Colorectal cancer （CRC） is one of the leading causes of cancer-related deaths, and inflammatory bowel diseases and dysregulated cell proliferation play important roles in colorectal carcinogenesis. Therefore, inhibition of inflammatory signaling and cell proliferation is used as a major strategy for chemoprevention of CRC. In the present study, it was found that IC5, a dithiocarbamate derivative, could inhibit the proliferation of LoVo human colon cancer cells in a concentration-dependent manner, with an IC50 of 22 gM. The anti-proliferation effect of IC5 was accompanied by a significant cell cycle arrest in G2/M phase. Further study revealed that IC5 significantly inhibited NF-~B signaling in LoVo cells, suggesting that IC5 could inhibit inflammatory responses. We then evaluated the in vivo efficacy of IC5 to inhibit colitis-associated colorectal carcinogenesis using an azoxymethane （AOM）/dextran sodium sulfate （DSS） mouse model. AOM/DSS treatment resulted in a CRC incidence of 58.3%, while the incidences were decreased to 37.5% and 25% in mice orally administered with 50 and 100 mg/kg IC5, respectively. In addition, IC5 also reduced the plasma levels of alanine aminotransferase and asparatate aminotransferase. Taken together, these results suggested that IC5 could prevent colitis-associated colorectal carcinogenesis, and more attention should be paid to it as a cancer chemopreventive agent in further investigation.

Phase engineering of two-dimensional transition metal dichalcogenides

Two-dimensional(2D) transition metal dichalcogenides(TMDs) have gained much attention in virtue of their various atomic configurations and band structures.Apart from those thermodynamically stable phases, plenty of metastable phases exhibit interesting properties. To obtain 2D TMDs with specific phases, it is important to develop phase engineering strategies including phase transition and phaseselective synthesis. Phase transition is a conventional method to transform one phase to another, while phase-selective synthesis means the direct fabrication of the target phases for2D TMDs. In this review, we introduce the structures and stability of 2D TMDs with different phases. Then, we summarize the detailed processes and mechanism of the traditional phase transition strategies. Moreover, in view of the increasing demand of high-phase purity TMDs, we present the advanced phase-selective synthesis strategies. Finally, we underline the challenges and outlooks of phase engineering of 2D TMDs in two aspects-high phase purity and excellent controllability. This review may promote the development of controllable phase engineering for 2D TMDs and even other2D materials toward both fundamental studies and practical applications.

From titanates to TiO_2 nanostructures: Controllable synthesis, growth mechanism, and applications

The design and fabrication of nanostmctures based on titanium dioxide （TiO2） have attracted much attention because of their low cost, non-toxicity, stability, and potential applications in industry and technology. Recently, one-dimensional （1 D） struc- tured titanates have been used as titanium source to prepare TiO2 nanostructures with various crystalline phases, shapes, sizes, exposed facets, and hierarchical structures. Among the synthetic strategies, hydrothermal method is a facile route to controlla- ble preparation of well-crystalline TiO2 in one step. Herein, we review our recent progress in transferring 1D titanates into TiO2 nanostructures through hydrothermal method, including the transformation mechanism and applications.

The adsorption and dissociation of multilayer CH_3OH on TiO_2(110)

The adsorption and dissociation of CH3OH on TiO2 （110） were studied using density functional theory methods. Our results suggest that CH3OH molecules can adsorb up to 3/4 ML （1 ML=5.2× 10^14 molecules/cm2） coverage at five-coordinated titanium （Tisc） sites to form the first layer. In the second layer, the CH3OH is adsorbed at bridge-bonded oxygen, and from the third layer, the CH3OH molecules form a hydrogen-bonded network with each other. The theoretical results show that dissociation of multilayer adsorbed methanol to aldehyde occurs through a stepwise pathway, with easy O-H bond dissociation and rate-determining C-H bond dissociation. The dissociation barriers for 8 or 12 CH3OH molecules on TiO2 are higher than that for low coverage by 0.15-0.21 eV; this suggests that the dissociation of multilayer adsorbed CH3OH is harder.

A simple approach to porous low-temperature-sintering BaTiO_3

Porous tetragonal BaTiO 3 ceramic was successfully prepared by a combination of hydrothermal and low-temperature-sintering method.The hollow TiO2@BaCO 3 as the sintering precursor was synthesized via a simple hydrothermal method,and then porous BaTiO 3 was generated by calcining the hollow TiO2@BaCO 3 precursor at 900 ℃ without additive.The hollow TiO2@BaCO 3 structure plays two important roles in the preparing of the porous BaTiO 3 ceramic.First,the TiO2@BaCO 3 hollow structure provides high surface areas and increases the contact points between BaCO 3 and TiO2,which can reduce the sintering temperature of the BaTiO 3 ceramic.Second,the cavity of the ordered arranged TiO2@BaCO 3 hollow sphere shows important influence on the porous structure,and the pore size of the as-prepared porous BaTiO 3 ceramic can be tuned from several nanometers to hundreds nanomters by changing the sintering temperature.The formation mechanism of the porous BaTiO 3 ceramic was proposed.

The internal structure models of Europa

We model the interior of Europa using a method by which we set three layers of Europa and the composition of each layer in advance. Comparing the calculated mass and radius related to each model with the data derived by the observations, we propose three possible internal structure models for Europa. All models are assumed to be differentiated into a metallic core, a (Mg,Fe)2SiO4 silicate mantle and an outer water shell. The only difference amongst these models are the composition of the core. The core of Model I is composed of Fe, while Model II composed of FeS, and the two models are based on the inferences provided by Europa's external gravitational field. Model III has a core which consists of Fe-FeS alloy, similar to that of Earth's outer core. Model I has a Fe core with a radius of 431 km, a (Mg,Fe)2SiO4 mantle with 999 km and a water shell with 132 km. Model II has a 777 km FeS core, a 619 km (Mg,Fe)2SiO4 mantle and a 167 km water shell. Model III has a 571 km Fe0.8(FeS)0.2 core, a 832 km (Mg,Fe)2SiO4 mantle and a 166 km water shell. In all three models, the density range and the radius of each layer is consistent with those deduced by Anderson et al.