Synthesis and structure of the unsymmetrical β-diimine precursor: The β-iminoamine

The reaction of benzoylacetone with ortho-substituted aniline derivatives gives the unsymmetrical β-iminoamine ligands (5–8) with high yields. A convenient synthesis is described. These compounds have been characterized by NMR and IR spectroscopies. The structure of the β-iminoamine 5, 3-N-(2,6-diisopropylphenylamino)-1-phenyl-1N-(2,6-diisopropylphenylimino)but-2-ene, was solved by X-ray diffraction methods.     

The Influence of Mind Mapping on Eighth Graders’ Science Achievement

This study assessed the influence of using mind maps as a learning tool on eighth graders’ science achievement, whether such influence was mediated by students’ prior scholastic achievement, and the relationship between students’ mind maps and their conceptual understandings. Sixty‐two students enrolled in four intact sections of a grade 8 science classroom were randomly assigned to experimental and comparison conditions. Participants in the experimental group received training in, and constructed, mind maps throughout a science unit. Engagement with mind mapping was counterbalanced with involving the comparison group participants with note summarization to control for time on task as a confounding variable. Otherwise, the intervention was similar for both groups in all respects. A multiple choice test was used to measure student gains across two categories and three levels of achievement. Data analyses indicated that the experimental group participants achieved statistically significant and substantially higher gains than students in the comparison group. The gains were not mediated by participants’ prior scholastic achievement. Analyses also indicated that iconography was not as central to participants’ mind maps as often theorized. Depicting accurate links between central themes and major and minor concepts, and using colors to represent concepts were the major aspects that differentiated the mind maps built by students who achieved higher levels of conceptual understanding.     

A Study of the Phase Transition in the System [Ag1−x(Na)x]NO3 by Infrared Spectroscopy

A complete infrared study of the mixed crystal system of AgNO₃ and NaNO₃ is carried out in the region 400–4000 cm^?1. The study includes internal fundamental normal vibrations of the NO^?₃ ion in the ordered and disordered phases of AgNO₃ at different values of the sodium concentration, the I.R. spectra, spectral band shape intensities, and frequencies of the internal modes as functions of the sodium ion concentration. Special attention is paid to bending mode, combination mode, asymmetric stretching mode, and over-tone. The rotational energy barrier is determined at different concentrations of the sodium ions in the system.     

Controlling pollution and environmental absorption capacity

This pollution accumulation model shows that the environmental absorption capacity is impacted by economic activity. The resulting optimal control problem has two inter-related state variables: the stock of pollution and the absorption capacity of the environment. The stock of pollution decreases with environmental absorption capacity and increases with the rate of current emissions, which is controlled by a production level as well as an emissions reduction effort. However, the environmental absorption capacity is positively affected by an absorption development effort, and negatively impacted by the stock of pollution. Under specific conditions, it is shown that an optimal path, which can be either monotonic or following transient oscillations, leads to a (nontrivial) saddle-point characterized by a positive environmental absorption capacity.     

The spectrophotometric and titrimetric determination of gold with ferroin as reagent

A spectrophotometric and a photometric titration method in a two-phase system for the determination of gold with ferroin is reported. Both methods are rapid and reproducible with an accuracy of ±1%. In the spectrophotometric determination Co²⁺, Cu²⁺, Ni²⁺ , Fe³⁺, Zn²⁺, Mn²⁺ and Cr³⁺ do not interfere with the determination of gold and Pt⁴⁺, Pd²⁺, Hg²⁺, Ir⁴⁺ and Os⁴⁺ can be tolerated up to a ratio of 1:1. The titrations can also be carried out in the presence of a number of diverse ions, e.g. Ni²⁺, Cu²⁺, Co²⁺, Fe³⁺, Zn²⁺, Cr³⁺, Mn²⁺, without interference; the platinum metals and Hg²⁺ cause interference but, by the use of the spectrophotometric procedure, this can be reduced.     

Mg-LDH Nanoclays Intercalated Fennel and Green Tea Active Ingredient: Field and Laboratory Evaluation of Insecticidal Activities against Culex pipiens and Their Non-Target Organisms

(1) Background: Mosquito control with essential oils is a growing demand. This work evaluated the novel larvicidal and adulticidal activity of fennel and green tea oils and their Layered double hydroxides (LDHs) nanohybrid against Culex pipiens (Cx. pipiens) in both laboratory and field conditions and evaluated their effect against non-target organisms; (2) Methods: Two types of nanoclays, MgAl-LDH and NiAl-LDH were synthesized and characterized using PXRD, TEM and SEM, whereas their elemental analysis was accomplished by SEM-EDX; (3) Results: Mg and Ni LDHs were synthesized by the co-precipitation method. The adsorption and desorption of active ingredients were conducted using LC MS/MS, with reference to the SEM-EXD analysis. The desorption process of MgAl-LDH intercalated green tea oil was conducted using ethanol, and reveled significant peaks related to polyphenols and flavonoids like Vanillin, Catechin, Daidzein, Ellagic acid, Naringenin, Myricetin and Syringic acid with concentrations of 0.76, 0.73, 0.67, 0.59, 0.52, 0.44 and 0.42 μg/g, respectively. The larvicidal LC₅₀ values of fennel oil, Mg-LDH-F, and Ni-LDH-F were 843.88, 451.95, 550.12 ppm, respectively, whereas the corresponding values of green tea were 938.93, 530.46, and 769.94 ppm. The larval reduction percentage of fennel oil and Mg-LDH-F reached 90.1 and 96.2%, 24 h PT and their persistence reached five and seven days PT, respectively. The reduction percentage of green tea oil and Mg-LDH-GT reached 88.00 and 92.01%, 24 h PT and their persistence reached five and six days PT, respectively. Against adults, Mg-LDH-GT and Ni-LDH-GT were less effective than green tea oil as their LC₉₅ values were 5.45, 25.90, and 35.39%, respectively. The reduction in adult density PT with fennel oil, Mg-LDH-F, green tea oil, and Mg-LDH-GT reached 83.1, 100, 77.0, and 99.0%, respectively, 24 h PT and were effective for three days. Mg-LDH-GT and Mg-LDH-F increased the predation Cybister tripunctatus (71% and 69%), respectively; (4) Conclusions: For the first time, Mg-LDH-GT and Mg-LDH-F was the best system loaded with relatively good desorption release to its active ingredients and significantly affected Cx. pipiens larvae and adults in both laboratory and field circumstances, and it could be included in mosquito control.     

About the singularities and bifurcations of double indices recursion sequences

This paper reports analytical and numerical investigations about the singularities and bifurcations of a new class of discrete dynamical systems defined generally by the following 2-D discrete systems: y _m+1,n+1=f(y _m,n ,y _m+1,n ,y _m,n+1); we consider particularly the case y_m+1,n+1 = f(y_m,n, y_m+1,n)y_{m+1,n+1} = f(y_{m,n}, y_{m+1,n}).     

Density functional theory study of hydrogen storage on Ni-doped C59X (X = B,N) heterofullerene

ABSTRACT

Hydrogen storage reactions on Ni ? C₅₉X(X = B, N) heterofullerene are investigated by using the state-of-the-art density functional theory calculations. The Ni atom prefers to bind at the bridge site between two hexagonal rings, and can bind up to five hydrogen molecules with average adsorption energies of (?0.94, ?0.48, ?0.33, ?0.25 and ?0.20 eV) per hydrogen molecule for Ni ? C₅₉B, while (?1.20, ?0.60, ?0.41, ?0.28 and ?0.23 eV) per hydrogen molecule for Ni ? C₅₉N. With no metal clustering, the system gravimetric capacities are expected to be as large as 10.87 and 10.85 wt % for 5H₂NiC₅₉B?and 5H₂NiC₅₉N, respectively. While the desorption activation barriers of the complexes 1H₂ + C₅₉X?(X = B, N)?are outside the Department of Energy domain (?0.2 to ?0.6 eV), the desorption activation barriers of the complexes nH₂ + C₅₉X(X = B, N)(n = 2 ? 5) are inside this domain. The hydrogen storage of the irreversible 1H₂ + NiC₅₉X?(X = B, N) and reversible 2H₂ + NiC₅₉X?(X = B, N) interactions is characterised in terms of density of states and projected densities of states, pairwise and non-pairwise additivity, infrared, Raman, electrophilicity and molecular electrostatic potentials.