A male-specific SCAR DNA marker and sex ratio of seedlings in salak(Salacca zalacca var.zalacca)

A male-specific SCAR DNA marker was developed using a RAPD DNA marker specific for male plants of Salacca zalacca var. zalacca （salak palm）. The marker is 1579 bp long and has a GC content of 38.5 %. Its sequence contains 1 or 2 open reading frames, indicating the marker is probably a coding region. No highly similar sequences were found in a search of the GenBank database. Sexes were identified using the SCAR DNA marker for three kinds of seedlings grouped by the number of seeds per fruit （1, 2 or 3）. The sex ratio of female to male did not differ significantly from 1：1 for the three kinds of seedlings, implying that the number of seeds per fruit is not a reliable index to identify the sex of a seedling.

Optimum nitrogen fertilization of Calophyllum inophyllum seedlings under greenhouse conditions

A greenhouse pot experiment was conducted to study the effects of nitrogen fertilization on Calophyllum inophyllum seedlings grown with 0, 50, 100, 150,200, 300, 400 and 600 mg N per seedling according to exponential functions. Seedling height, root collar diameter, leaf area and total biomass increased with increasing fertilization from 0 to 200 mg N per seedling and decreased with further increase in fertilization from300 to 600 mg N per seedling. The net photosynthetic rate,stomatal conductance, intercellular CO_2 concentration and transpiration rate of C. inophyllum seedlings showed a unimodal parabolic trend, with peak values of7.29 mmol·m^(–2)·s^(–1), 0.071 mol·m^(–2)·s^(–1), 220 mmol·mol^(–1) and 1.34 mmol·m^(–2)·s^(–1), respectively, when the rate of fertilization was 200 mg N per seedling. Photosynthetic gas exchange parameters were significantly different among nitrogen treatments. Based on the critical values of leaf N and P concentration and N/P ratio, the optimum amount of nitrogen of C. inophyllum seedlings was 200–400 mg per seedling for leaf N and P concentration, and100–400 mg per seedling for N/P ratio. It was concluded that 200–400 mg N per seedling was the most suitable nitrogen range for C. inophyllum seedlings.

Aggregation-induced emission enhancement of yellow photoluminescent carbon dots for highly selective detection of environmental and intracellular copper(Ⅱ) ions

Carbon dots (CDs) are prepared through a simple one-step hydrothermal treatment of o-phenylendiamine (OPD) and show yellow photoluminescent (PL) emission under the ultraviolet excitation, which can be further enhanced by Cu2+ ions owing to Cu2+ ions induced aggregation of OPD-CDs through the coordination of Cu2+ with amino groups on the surface of OPD-CDs. The aggregation induced emission enhancement (AIEE) property enables it feasible to develop a simple, sensitive and selective method to detect environmental and intracellular copper (Ⅱ) ions. The limit of detection as lowas 0.28 μmol/L (3σ/k) and a dynamic range from 0.5 μmol/L to 40 μmol/L make it veryeasy to detect the copper content inwater samples, such as river closure reservoir. Furthermore, fluorescence imaging of intracellular Cu2+ suggests that the AIEE features of OPD-CDs specific to Cu2+ ions can be also applied in biological systems.

A modified forward and backward reaching inverse kinematics based incremental control for space manipulators

Forward and backward reaching inverse kinematics(FABRIK)is an efficient two-stage iterative solver for inverse kinematics of spherical-joint manipulator without the calculation of Jacobian matrix.Based on FABRIK,this paper presents an incremental control scheme for a free-floating space manipulator consists of revolute joints and rigid links with the consideration of joint constraints and dynamic coupling effect.Due to the characteristics of FABRIK,it can induce large angular movements on specific joints.Apart from that,FABRIK maps three dimensional(3D)problem into two dimensional(2D)problem by a simple geometric projection.This operation can cause infinite loops in some cases.In order to overcome these issues and apply FABRIK on space manipulators,an increments allocation method is developed to constrain the angular movements as well as to re-orient the end-effector.The manipulator is re-positioned based on the momentum conservation law.Instead of pure target position tracking,the orientation control of the end-effector is also considered.Numerical simulation is performed to testify and demonstrate the effectiveness and reliability of the proposed incremental control approach.