Synthesis of New Brassinosteroid 24-Norcholane Type Analogs Conjugated in C-3 with Benzoate Groups

The metabolism of brassinosteroid leads to structural modifications in the ring skeleton or the side alkyl chain. The esterification and glycosylation at C-3 are the most common metabolic pathways, and it has been suggested that conjugate brassinosteroids are less active or inactive. In this way, plants regulate the content of active brassinosteroids. In this work, the synthesis of brassinosteroid 24-norcholane type analogs conjugated at C-3 with benzoate groups, carrying electron donor and electron attractant substituents on the aromatic ring, is described. Additionally, their growth-promoting activities were evaluated using the Rice Lamina Inclination Test (RLIT) and compared with that exhibited by brassinolide (used as positive control) and non-conjugated analogs. The results indicate that at the lowest tested concentrations (10⁻⁸–10⁻⁷ M), all analogs conjugated at C-3 exhibit similar or higher activities than brassinolide, and the diasteroisomers with S configuration at C-22 are the more active ones. Increasing concentration (10⁻⁶ M) reduces the biological activities of analogs as compared to brassinolide.     

Crystal structures and luminescence of two cadmium(II) polymers constructed from aromatic polycarboxylate and bis(1,2,4-triazol-1-yl)methane ligands

Two new coordination compounds, {[Cd₂(btrm)(ip)₂(H₂O)₂]?·?2H₂O} _n (1) and {[Cd₂(btrm)(hip)₂(H₂O)₄]?·?3H₂O} _n (2) (btrm?=?bis(1,2,4-triazol-1-yl)methane, H₂ip?=?isophthalic acid, H₂hip?=?5-hydroxy isophthalic acid), have been synthesized and structurally characterized. Compound 1 is a 3-D network with CdSO₄ topology. Compound 2 contains 1-D ladder structures, which are interconnected by classical hydrogen-bonding interactions (O–H?···?O) to lead to 3-D supramolecular architectures. Luminescence was performed on 1 and 2, both of which showed strong fluorescent emissions in the solid state at room temperature.     

Two fluid flow and heat transfer in an inclined channel containing porous and fluid layer

Convective flow and heat transfer in an inclined channel bounded by two rigid plates held at constant different temperatures with one region filled with porous matrix saturated with a viscous fluid and another region with a clear viscous fluid different from the fluid in first region is studied analytically. The coupled nonlinear governing equations are solved using regular perturbation method. It is found that the presence of porous matrix in one of the region reduces the velocity and temperature. Results have been presented for a wide range of governing parameters such as Grashof number, porous parameter, angle of inclination, ratio of heights of the two layers and also the ratio of viscosities.     

高精度激光倾角测量技术研究

本文提出了一种高精度激光电子二维倾角测量技术,该技术利用液体表面多次光反射,将倾角变化转换成激光光斑的位移,并通过多次光学反射实现光学放大,从而实现了倾角和倾角变化的高精度测量.利用本技术实现的倾角测量仪器具有测量精度高、体积小等优点,经过标定试验系统测量精度达到2.5″.高精度激光电子二维倾角测量系统可广泛应用于水坝安全监测工程、各种建筑和检测领域.     

猫眼动镜横移误差容限及次镜倾斜分析

介绍了猫眼动镜干涉光谱仪的基本原理和三种猫眼镜,分析了猫眼动镜的横向偏移对干涉图的影响,推导了横移所产生的最大附加光程差公式,从相位误差角度给出了猫眼动镜的横移误差容限公式并得到了在典型参量下的定量数据．分析了猫眼镜次镜倾斜对光程差的影响,导出了次镜倾斜所产生的最大附加光程差公式,并给出了在典型参量下最大附加光程差与次镜倾角之间的关系图．     

Effects of inclination angle on natural convection in enclosures filled with Cu–water nanofluid

Effects of inclination angle on natural convection heat transfer and fluid flow in a two-dimensional enclosure filled with Cu-nanofluid has been analyzed numerically. The performance of nanofluids is tested inside an enclosure by taking into account the solid particle dispersion. The angle of inclination is used as a control parameter for flow and heat transfer. It was varied from  = 0° to  = 120°. The governing equations are solved with finite-volume technique for the range of Rayleigh numbers as 10³  Ra  10⁵. It is found that the effect of nanoparticles concentration on Nusselt number is more pronounced at low volume fraction than at high volume fraction. Inclination angle can be a control parameter for nanofluid filled enclosure. Percentage of heat transfer enhancement using nanoparticles decreases for higher Rayleigh numbers.     

On the behavior of suspension of drops on an inclined surface

The flow of drops suspended on an inclined surface, are studied by numerical simulations at finite Reynolds numbers. The flow is driven by the acceleration due to gravity, and there is no pressure gradient in the flow direction. The effect of the Reynolds number, the Capillary number and density ratio on the distribution of drops and the fluctuation energy across the channel are investigated. It is found that drops tend to stay away from the channel floor, which is consistent with the behavior observed in the granular flow regime. Drops that are less deformable will stay further away from the channel floor. Also, drops appear at a larger distance from the floor as the Reynolds number increases. Simulations at large density ratios show that results are more compatible with computer simulations of granular flows. The behavior observed here resembles more the granular flow regime when the restitution coefficient is low.     

一种带温度补偿的数字倾斜角测量系统

提出了一种带温度补偿的数字倾斜角测量系统,阐述了系统组成、温度补偿原理和软件设计,采用电子倾角器、A/D转换器、单片机、温度传感器实现了在宽工作温度范围内的倾斜角测量,消除了环境温度变化引起的偏差.系统通过实验验证,达到了较高的测量准确度,并在某项目的水平倾斜角测量系统中得到应用.     

Evaporation heat transfer of R-134a inside a microfin tube with different tube inclinations

An experimental investigation has been carried out to study the heat transfer characteristics during evaporation of R-134a inside a single helical microfin tube. The microfin tube has been provided with different tube inclination angles of the direction of fluid flow from horizontal, α. The experiments were performed for seven different tube inclinations, α, in a range of −90° to +90° and four mass velocities of 53, 80, 107 and 136 kg/m² s for each tube inclination angle during evaporation of R-134a. The results demonstrate that the tube inclination angle, α, affects the boiling heat-transfer coefficient in a significant manner. For all refrigerant mass velocities, the best performing tube is that having inclination angle of α = +90°. The effect of tube inclination angle, α, on heat-transfer coefficient, h, is more prominent at low vapor quality and mass velocity. An empirical correlation has also been developed to predict the heat-transfer coefficient during flow boiling inside a microfin tube with different tube inclinations.     

CODIMENSION 3 BIFURCATIONS OFHOMOCLINIC ORBITS WITH ORBITFLIPS AND INCLINATION FLIPS

The homoclinic bifurcations in four dimensional vector fields are investigated by setting up a local coordinates near the homoclinic orbit. This homoclinic orbit is non-principal in the meanings that its positive semi-orbit takes orbit flip and its unstable foliation takes inclination flip. The existence, nonexistence, uniqueness and coexistence of the 1-homoclinic orbit and the 1-periodic orbit are studied. The existence of the twofold periodic orbit and three-fold periodic orbit are also obtained.