Electric Conductivity of Glasses in the MgO–V2O5–P2O5 System

Russian Journal of Electrochemistry - Amorphous glasses of the composition xMgO–yP2O5– (100 – x – y)V2O5 with x = 1–5 and y = 5, 10, and 15 mol % are obtained by the...     

On the Electric Field Effect on the Dynamics of High Rydberg States of Hydrogen Atom and the Model of ZEKE Spectroscopy

In this paper, the studies of the dynamics of the high Rydberg states for n = 10 and n = 100 of hydrogen atom under the influence of an electric field will be reported. It will be shown from our calculated results that the two time constants of τ_slow ≈? 1 – 10 μs and τ_fast ≈? 1 – 10 ns obseved in ZEKE experiments are obtained in the stray field condition, i.e., F = 10 – 100 mV/cm. To treat the ZEKE states of complex systems like many-electron atoms, molecules, clusters etc., the inverse Born-Oppenheimer approximation can be used and it will be discussed.     

Spectrophotometric Determination of Phenols and Cyanides After Distillation from Natural Waters

Abstract

Total phenols were determined by molecular spectrophotometry, after distillation, complexation with 4-aminoantipyrine and extraction into chloroform. Cyanides were also determined spectrophotometrically after distillation from the acidified samples, and complexation in moderate acidic solution with barbituric acid. The dynamic ranges were 0 – 100 μg L^?1 for total phenols and 0 – 30 μg L^?1 for cyanides. The above methods were applied in the analysis of river, lake and stream waters collected from Northern Greece. The seasonal and spatial variation of concentrations was evaluated by two-way ANOVA. Background levels (4 – 12 μg L^?1 for total phenols and 0.3 – 3 μg L^?1 for cyanides), were found in almost all surface waters, with some exceptions.     

Three New Polyyne (=Polyacetylene) Glucosides from the Edible Roots of Codonopsis cordifolioidea

Three new linear C₁₄ polyyne (=polyacetylene) glucosides, cordifolioidynes A–C ( 1 – 3 ), together with two known polyynes, lobetyol ( 4 ) and lobetyolin ( 5 ), and five known phenylpropanoids, i.e., sinapinaldehyde ( 6 ), coniferaldehyde ( 7 ), coniferoside ( 8 ), sachaliside ( 9 ), and isoconiferin ( 10 ), were isolated from the roots of Codonopsis cordifolioidea. The structures of 1 – 3 were established from spectral evidences and by characterization of their hydrolysis products. Acid hydrolysis of 1 afforded the aglycone 1a , while hydrolysis of 2 and 3 gave the cyclization products 2a and 3a , respectively. Compounds 4 – 10 were isolated from this plant for the first time. The antibacterial activity of compounds 1 – 5 were assessed against eight microbial strains by the agar dilution method, none of them exhibited antibacterial effects at concentrations up to 100 μg/ml.     

Unit cloning and amplification as novel and universal strategies for complex vector construction and small DNA fragment preparation

With a novel and universal strategy for the cloning of multiple DNA fragments, a complex synthetic vector (pVEC100), harboring the target DNA fragments in conventional 100‐bp DNA ladder, was constructed for efficient and large‐scale production of 100‐bp DNA marker through bacteria fermentation, plasmid extraction and restrictive digestion. Since the restrictive digestion of complex vectors yields insufficient small DNA fragments, an innovative PCR model was developed as an alternative. The PCR model comprised a specially designed template vector and a unit amplification model for producing groups of small DNA fragments. The unit amplification model improved the efficiency of the PCR protocol and made it more economical and easier for small DNA fragment amplification. The approach presented in this paper – a unit cloning model for constructing complex synthetic vectors combined with the modular design of unit amplification by PCR – is a powerful method for preparing small DNA fragments of DNA molecular weight standards.     

Synthesis, Crystal Structure, and Herbicidal Activities of 2-Cyanoacrylates Containing 1,3,4-Thiadiazole Moieties

Three series of novel 2‐cyanoacrylates 7a – 7f , 9a – 9f , 10a – 10f containing 1,3,4‐thiadiazole ring moieties were synthesized as herbicidal inhibitors of photosystem II (PS II) electron transportation. Their structures were clearly verified by ¹H NMR, ¹³C NMR, elemental analysis (or HRMS analysis) and single‐crystal X‐ray diffraction analysis. Bioassay showed that a suitable group at the 3‐position of acrylates was essential for high herbicidal activity. In particular, compound 7e showed the best herbicidal activities and gave 100% inhibitory activity against rape and amaranth pigweed at a dose of 1.5 kg/ha. Introduction of substituent with higher polarity such as sulfinyl or sulfonyl to the 5‐position of 1,3,4‐thiadiazole decreased herbicidal activities.     

An Efficient Synthesis of Novel Benzo‐Fused Macrocyclic Dilactams

A facile synthetic approach was adopted towards the synthesis of benzo‐fused macrocyclic lactams 2a – 2g via the base‐catalyzed condensation reaction of 2,2′‐[alkanediylbis(oxy)]bis[benzaldehydes] 3a – 3c with N,N′‐substituted bis[2‐cyanoacetamide] derivatives 7a – 7c (Scheme 2). The latter compounds were obtained by the reaction of the appropriate diamines 6a – 6c with ethyl 2‐cyanoacetate ( 4 ). Attempts to prepare the oxaaza macrocycles 2 by alternative pathways were also investigated. The novel pyrazolo‐fused macrocycles 13a and 13b were obtained in 48 and 52% yield, respectively, upon treatment of 2d and 2g with NH₂NH₂?H₂O at 100° (Scheme 4).     

New Briaranes from the South China Sea Gorgonian Junceella fragilis

Three new briarane diterpenes, junceellonoids C–E ( 1 – 3 ), along with six known briaranes, junceellin A ( 4 ), praelolide ( 5 ), and junceellolides A‐D ( 6 – 9 ), were isolated from the EtOH/CH₂Cl₂ extracts of the South China Sea gorgonian coral Junceella fragilis. The structures of 1 – 3 were established by extensive spectroscopic analysis, including 1D‐ and 2D‐NMR data. Compounds 1 and 2 exhibited mild cytotoxicity against human galactophore carcinoma (MDA‐mB‐231 and MCF‐7) cells at the concentration of 100 μM .     

The Chemistry of Protactinium

Protactinium exhibits an ambivalent chemical behavior. In non-aqueous solutions and in the solid state, both quadrivalent and quinquevalent protactinium has properties which characterize it as a typical actinide element. On the other hand, investigations in aqueous solution show quinquevalent protactinium to be a homologue of niobium and tantalum. It exhibits – except in hydrofluoric acid solutions – a marked tendency to undergo irreversible hydrolysis and condensation reactions, which leads to the situation that tracer amounts (ca. 10^?12 mole/l) and macroscopic amounts (10^?3–10^?6 mole/l) of protactinium often behave differently. Reduction with strong reducing agents gives aqueous solutions of Pa(IV), the properties of which again correspond in general to those of Th(IV) and show no relation to Nb(IV). Our knowledge of the chemical behavior of this rare radioelement has been advanced, in particular, by the production in 1958–1960 of 100 g of pure protactinium – the largest amount so far – from residues of the British production of uranium.     

Applications of electrospray laser desorption ionization mass spectrometry for document examination

We have employed electrospray laser desorption ionization mass spectrometry (ELDI‐MS) to rapidly characterize certain classes of compounds – the inks within the characters made by inks and inkjet printer on regular paper and the chemical compounds within thermal papers. This ELDI‐MS approach allowed the ink and paper samples to be distinguished in terms of their chemical compositions. Sample pretreatment was unnecessary and the documents were practically undamaged after examination. The ink chemicals on the documents were desorbed through laser irradiation (sampling spot area: <100 µm²); the desorbed molecules then entered an electrospray plume – prepared from an acidic methanol/water solution (50%) – where they became ionized through fusion or ion‐molecule reactions with the charged solvent species and droplets in the plume. Copyright © 2009 John Wiley & Sons, Ltd.     

Fluorescent Optosensor for Humidity Measurements in Air

A fiber‐optic sensor for relative‐humidity (RH) monitoring in environmental samples is described based on the adiabatic photoreaction that produces an intramolecular charge‐transfer excited state, which is the basis of the sensor response. The sensitive membranes are obtained immobilizing a highly fluorescent dye, 4‐[2‐(pyrazin‐2‐yl)‐1,3‐oxazol‐5‐yl]benzenamine (pzoxba; formerly called appzox), in hydroxypropylcellulose (HPC). The composition of the sensing films was optimized to a final ratio pzoxba/HPC of 1.8⋅10⁻⁵ mol g⁻¹ with a 100‐μm membrane thickness. The optode response spans from 1.68 to 100% RH, with a detection limit of 0.56% (Table 2). Typical response times (t₉₀) to 0 – 100% relative humidity are 1 – 2 min, the relative standard deviation for repeated measurements being 0.77 – 1.8%. The optode is insensitive to typical organic vapor interferents of commercial capacitive sensors (see Table 3) as well as to molecular oxygen, an important quencher of other luminescence‐based optical sensors. The proposed optode was successfully applied and validated for continuous monitoring of the relative humidity level in environmental samples.     

Design,Synthesis, and Anticancer Activities of Benzofuran–Isatin Hybrids Tethered by Pentylene and Hexylene

Fourteen benzofuran–isatin hybrids 6a – f and 7a – h tethered via alkyl linker (pentylene and hexylene) were designed and synthesized, and hybrids 6c – f and 7a – h were screened for their in vitro anticancer activity against various human cancer cell lines. The majority of the hybrids were active against the tested cancer cells, and the most active hybrids 7g (half maximal inhibitory concentration/IC₅₀: 77.2–88.9 μM) and 7h (IC₅₀: 65.4–89.7 μM), which possessed broad spectrum anticancer activity were as potent as the reference vorinostat (IC₅₀: 64.2–>100 μM) against all tested cancer cell lines, could act as leads for further investigations. The structure–activity relationship is also discussed, and the enriched structure–activity relationship may afford useful information for further rational design of the candidates with higher activity.     

Polymer‐Supported Ionic‐Liquid‐Catalyzed Synthesis of 1,2,3,4‐Tetrahydro‐ 2‐oxopyrimidine‐5‐carboxylates via Biginelli Reaction

The Biginelli reaction between an aromatic aldehyde, ethyl acetoacetate, and urea – catalyzed by polymer‐supported, re‐usable, room‐temperature ionic liquids (RTIL) such as 1b – was shown to efficiently proceed in glacial AcOH at 100° to afford the corresponding pyrimidine‐5‐carboxylates 3 in yields up to 99% within 2 h (Table 2). The catalyst(s) could be reused at least five times, basically without loss of activity, which makes this transformation not only straight‐forward, but also considerably less expensive compared to methods involving classical RTIL catalysts.     

Magnetic Interaction between Iron Particles in Lithium Phosphate Systems

Russian Journal of Physical Chemistry A - The glasses from the system xFe2O3(100 – x)[P2O5 · Li2О] with 0 &lt; x &lt; 50 mol % are studied. These materials have been...     

Lengthy Rod Formation from a Poly(oxyalkylene)amine‐Intercalated Smectite Clay by a Self‐Aligning Mechanism

Summary: A micrometer rod morphology was produced by self‐assembly of poly(oxypropylene)amine (POP‐amine) modified montmorillonite. The requisite primary structure was prepared by intercalation of the layered clay with POP‐amine salts. During the drying process, the primary units self‐assemble into micro‐rods that are 100–800 nm wide and 2–40 μm long. The stacking process may involve two complimentary forces – the POP hydrophobic effect and the silicate ionic interaction – acting in separate directions.

Lengthy rod formation from Poly(oxyalkylene)amine‐intercalated smectite clay.     

Radiation curable materials – principles and new perspectives

Increasing environmental concerns and the ensuing legislation to cut emissions of volatile organic compounds (VOCs) have been major driving forces behind the development of radiation cured coatings over the past 25 years. Today radiation cured coatings are known for their good overall performance and their excellent resistance against chemical and physical surface damages. Advanced photoinitiator systems allow the light stabilisation of UV‐curable formulations and the outdoor application of the coating. The rapid curing, combined with the possibility of immediate processing of the coated objects opens the way for radiation curing – in 100%‐, water based‐, and dual cure systems as well as for radiation curable powder coatings – for a wide variety of application.     

Preconcentration of some metals using metalfix chelamine resin prior to ICP-AES analysis

Preconcentration and separation of Ni, Pb and Cd have been investigated using the metalfix chelamine resin prior to inductively coupled plasma – atomic emission spectrometry (ICP-AES) under various experimental conditions. The recoveries of the analytes obtained with 95% confidence level were 92 ± 1% for Ni, 100 ± 4% for Pb and 93 ± 3% for Cd.     

Three New Benzophenone Glucosides from the Leaves of Planchonella obovata

Chemical investigation of the EtOH extract of the leaves of Planchonella obovata resulted in the isolation of four benzophenone glucosides, 1 – 4 , of which three, 2 – 4 , are new chemical entities together with five known flavonol glycosides. Their structures were elucidated by spectroscopic analysis. Among the isolated compounds, iriflophenone 2‐O‐(2,6‐di‐O‐galloyl)‐β‐D ‐glucopyranoside ( 4 ) showed some activity (91.4 and 15.0% inhibition at 100 and 10 μg/ml, resp.) against the α‐glucosidase of Bacillus stearothermophilus.