Alleviation of adverse effects of drought stress on growth and some potential physiological attributes in maize (Zea mays L.) by seed electromagnetic treatment

Effects of varying preseed magnetic treatments on growth, chlorophyll pigments, photosynthesis, water relation attributes, fluorescence and levels of osmoprotectants in maize plants were tested under normal and drought stress conditions. Seeds of two maize cultivars were treated with different (T0 [0 mT], T1 [100 mT for 5 min], T2 [100 mT for 10 min], T3 [150 mT for 5 min] and T4 [150 mT for 10 min]) electromagnetic treatments. Drought stress considerably suppressed growth, chlorophyll a and b pigments, leaf water potential, photosynthetic rate (A), stomatal conductance (g(s)) and substomatal CO(2) concentration (C(i)), while it increased leaf glycinebetaine and proline accumulation in both maize cultivars. However, pretreated seeds with different magnetic treatments significantly alleviated the drought-induced adverse effects on growth by improving chlorophyll a, A, E, g(s), C(i) and photochemical quenching and nonphotochemical quenching, while it had no significant effect on other attributes. However, different magnetic treatments negatively affected the g(s) and C(i) particularly in cv. Agaiti-2002 under drought stress conditions. Of all magnetic treatments, 100 and 150 mT for 10 min were most effective in alleviating the drought-induced adverse effects. Overall, preseed electromagnetic treatments could be used to minimize the drought-induced adverse effects on different crop plants.     

Effects of surfactants on microwave-assisted solid-state intercalation of poly(carbazole) in Bentonite

The present preliminary investigation reports, for the first time, the effects of typical cationic and anionic surfactants on the microwave-assisted solid-state intercalation and polymerization of carbazole (Cz) in the basal spacings of Bentonite. The intercalation of cetyl pyridinium chloride (CPCl), a cationic surfactant, and naphthalene sulfonic acid (NSA), an anionic surfactant, in Bentonite was carried out at two loadings—25 and 50 wt%—using microwave irradiation. The in situ polymerization of Cz was successfully carried out into the surfactant-modified galleries of Bentonite. This was confirmed by Gel permeation chromatography (GPC). The intercalation of poly(carbazole) (PCz) was confirmed by FT-IR, UV–Visible, and XRD analyses. Although polymerization was carried out in the solid-state, the UV–Visible spectra revealed the doped state of PCz and the presence of a charge carrier tail. The XRD studies showed that the increase in the height of the galleries was higher in case of Bentonite/CPCl/PCz nanocomposites as compared to Bentonite/NSA/PCz nanocomposites. It also revealed different orientations of the two surfactants in the galleries of the clay. The average particle size of Bentonite/CPCl/PCz (1:0.25:0.25) and (1:0.5:0.5) nanocomposites was found to be in the range of 25–35 and 50–60 nm, respectively. The Bentonite/NSA/PCz (1:0.25:0.25) and (1:0.5:0.5) nanocomposites showed the average particle size in the range of 20–30 nm and 40–50 nm, respectively. The results revealed that both cationic and anionic surfactants strongly influenced the morphology of Bentonite/PCz nanocomposites. The difference in the mechanisms of solid-state intercalation of PCz in the presence of these surfactants has been proposed.     

液态水热容的量子校正

在不同温度下对液态水进行分子动力学模拟，研究各温度下液态水中各个原子的速度自相关函数密度谱，以考察液态水热容的量子校正随温度的变化规律．研究结果表明，水分子的三个内部振动模式对热容的量子校正不随温度变化，而转动和分子距平衡位置的摆动运动模式的量子校正随温度升高而逐步减小．对于分子动力学模拟结果经温度涨落计算所得的热容进行了量子校正，校正结果与实验值能符合．     

A facile and efficient synthetic approach to novel lariat macrocyclic diamides and bis macrocyclic diamides

The hydroxy macrocycles 8, 19a‐c were prepared in 40–55% yields by reacting the dipotassium salts 2a‐c with each of epichlorohydrin ( 7 ) and bis(chloromethyl) derivative 18 . Acylation of the hydroxyl group of each of 8, 19a‐c with 2‐chloroacetylchloride ( 9 ) in DMF gave the corresponding esters 10, 20a,b . Reaction of the latter with different amines as well as phenoxides furnished exclusively the target lariat macrocycles 13a‐c, 22a‐c and 23a‐c in 60–63% and 50–55% yields, respectively. Amination of two equivalents of the chloroacetyloxy derivative 10 and 2a,b with 1 equiv. of piperazine ( 12c ) afforded the corresponding bismacrocycles 14 and 26a,b respectively, in 60–65% yields. Moreover, the novel bis(macrocycles) 27–29 were prepared in 45–50% yields, respectively, by reacting each of 20a,b with the dipotassium salts 2b, 24 and 25 respectively, in DMF.     

Nonextractive procedure and precolumn derivatization with 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole for trace determination of trimetazidine in plasma by high-performance liquid chromatography with fluorescence detection

A highly sensitive high-performance liquid chromatographic method with fluorescence detection has been developed and validated in a single laboratory for the trace determination of trimetazidine (TMZ) in human plasma. Fluoxetine (FLX) was used as the internal standard. TMZ and FLX were isolated from plasma by protein precipitation with acetonitrile and derivatized by heating with 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole in pH 8 borate buffer at 70 degrees C for 30 min. Separations were performed in the isocratic mode on a Nucleosil CN column with the mobile phase acetonitrile-10 mM sodium acetate buffer (pH 3.5)-methanol (47 + 47 + 6, v/v/v) at a flow rate of 1.0 mL/min. The derivatized samples were excited at 470 nm and monitored at an emission wavelength of 530 nm. Under the optimum chromatographic conditions, a linear relationship with a good correlation coefficient (r = 0.9997, n = 5) was obtained for the peak area ratio of TMZ to FLX and for TMZ concentrations of 1-120 ng/mL. The proposed method has the lowest limits of detection and quantitation reported to date for the determination of TMZ in plasma with values of 0.3 and 0.95 ng/mL, respectively. The values for intra- and interassay precision were satisfactory; the relative standard deviations were < or =4.04%. The accuracy of the method was demonstrated; the recoveries of TMZ from spiked human plasma were 98.13-102.83 +/- 0.2-4.04%. The method has high throughput because of its simple sample preparation procedure and short run time (<10 min). The results demonstrated that the proposed method would have great value when applied in pharmacokinetic studies for TMZ.     

Computational study of combined effects of conduction-radiation and hydromagnetics on natural convection flow past magnetized permeable plate

The computational study of the combined effects of radiation and hydromagnetics on the natural convection flow of a viscous,incompressible,and electrically conducting fluid past a magnetized permeable vertical plate is presented.The governing non-similar equations are numerically solved by using a finite difference method for all values of the suction parameter ξ and the asymptotic solution for small and large values of ξ.The effects of varying the Prandtl number P r,the magnetic Prandtl number P r m,the magnetic force parameter S,the radiation parameter R d,and the surface temperature θ w on the coefficients of the skin friction,the rate of heat transfer,and the current density are shown graphically and in tables.An attempt is made to examine the effects of the above mentioned physical parameters on the velocity profile,the temperature distribution,and the transverse component of the magnetic field.     

Magnetic nanomaterials catalyzed synthesis of tetrazoles

Abstract

Tetrazoles are valuable molecules in pharmaceutical and agriculture chemistry, because they are excited in many drugs, natural products and biologically active molecules. During the last decade, magnetic nanomaterials have appeared as highly efficient catalysts in chemical science in general organic chemistry, because of their simple preparation, modification, and large surface area ratio. In this paper, we provide an overview of the utilization of magnetic nanomaterials as attractive and efficient catalytic systems in synthesis of biologically active tetrazoles.     

Isolation and structural determination of sorbinols A and B, new triterpenes from Sorbus cashmariana, by 1D and 2D NMR spectroscopy

Two new pentacyclic triterpenes, sorbinols A (1) and B (2) have been isolated from the ethyl acetate fraction of Sorbus cashmariana and their structures assigned from (1)H and (13)C NMR spectra, DEPT and by 2D COSY, NOE, HMQC and HMBC experiments. Both 1 and 2 showed moderate inhibitory potential against the enzyme lipoxygenase.     

Transport study of V(V), Zn(II) and Be(II) using supported liquid membranes

V(V), Zn(II) and Be(II) have been studied to test oxine and tri-n-butylphosphate (TBP) as carriers for transport through supported liquid membranes in polypropylene film. All the three types of ions can be passed through such membranes using oxine in case of V(V) and TBP in case of Zn(II) and Be(II). Maximum flux of metal ions has been observed from 0.01M H₂SO₄ for V(V) (3.22·10^–6 mol·m^–2·s^–1) and 2M HCl containing 3M CaCl₂ for Zn(II) solution (1.4·10^–6 mol·m^–2·s^–1). Low flux was observed in case of Be(II) since the membrane was affected by sulphocyanide group and did not remain hydrophobic. Mechanism of transport for these metal ions have been proposed separately. Distribution coefficient data for V(V) have also been evaluated to determine theoretical values of the permeability coefficient, and compared with experimental values.     

Validation of short run time LC-ESI (+) MS/MS method for determination of twenty recommended pesticide residues in food based on QuEChERS extraction technique

Food is expected to contain pesticide residues that might have many problems due to their toxicities for human and animals. So, it is very important to detect and quantify the pesticides contamination levels to increase food safety for the human. The target of our study is to analyse a 20 new pesticides including different pesticide classes such as 1 acaricide, 3 fungicides, 2 plant growth regulators, 11 herbicides, 1 insecticide, 1 rodenticide, and 1 metabolite which were selected according to their modern application in the Egyptian agriculture as well as the recommendation of the Egyptian Agriculture Pesticides Committee (APC). The research is focused on the method validation for the routine analysis of the targeted pesticide residues according to the European SANTE/11,813/2017 guideline. The validation was carried out by fortifying of three levels at 0.01, 0.05 and 0.1 mg/kg in four blank matrices: apple, green beans, fennel seeds and rice which represent different classes of food. The most common citrate buffered QuEChERS extraction method and liquid chromatography coupled with triple quadrupole mass spectrometry (LC-MS/MS) device were used. The mass spectrometer was operated in the positive electrospray ionisation ESI (+) mode and the non-scheduled multiple reactions monitoring (MRM) method in a short run time of 16.0 min. The limits of quantifications (LOQs) for all pesticides ranged between 0.01 and 0.05 mg/kg. Good linearity of the method was in the concentration range 0.001–0.5 μg/ml with acceptable correlation coefficients (r²) ≥ 0.99 for all analytes. The average recoveries for all the target pesticide residues were in the range of 70–120% with relative standard deviations RSDs ≤ 20%. The matrix effect was compensated by using the standard addition method. This short run time LC ESI (+) MS/MS Method may help laboratories which deal with the routine pesticide residues analysis in different food samples.