On weak spreadability of distributed-parameter systems and its achievement via linear--quadratic control techniques

In this paper, the concept of weak spreadability is introduced.It constitutes an extension of the idea developed by El Jai& Kassara. In the case of linear distributed systems weconsider quadratic control techniques with a conveniently penalizedcriterion which makes the system weakly spreadable. The approachis outlined for a convection—diffusion system, and theresults of a numerical study are also included to illustratethe main features of the considered problem.     

Analytical mass spectrometry

A review is made of the basic theory, instrumentation and application of mass spectrometry, with special reference to the development of the equipment and its impact on the scope of application.     

The gas chromatography, thermal analysis and mass spectrometry of fluorinated lead β-diketonates Determination of traces of lead by the integrated ion-current technique

Preparative details for perfluoroalkanoylpivalylmethanes and their lead chelates are given. Thermal analysis, gas chromatography and mass spectral studies all indicate high thermal stability, but strong column interaction makes successful quantitative gas chromatography difficult. The integrated ion-current technique is applied to determine lead heptafluorobutanoylpivalylmethanate in the range 10^-9–10^-7 g of lead, but a lower detection limit of ca. 10^-14 g is indicated.     

Beckmann rearrangement in benzophenone oxime,a mass spectrometric study

The isomerization of benzophenone oxime to benzanilide, previously observed to take place in the ion source of a mass spectrometer and attributed to a Beckmann type rearrangement of the benzophenone oxime molecule ion, has been shown to occur by a thermal mechanism prior to ionization. Mass spectrometric evidence is supplemented by infrared spectrophotometric examination of solid samples and shows that in the solid state, at room temperature, benzophenone oxime has a lifetime of about 600 h.     

Heat Capacities of Aqueous Solutions of Acetone; 2,5-Hexanedione; Diethyl Ether; 1,2-Dimethoxyethane; Benzyl Alcohol; and Cyclohexanol at Temperatures to 523 K

The heat capacities of aqueous solutions of acetone, 2,5-hexanedione, diethyl ether, 1,2-dimethoxyethane, benzyl alcohol and cyclohexanol at concentrations of 0.1 to 1.0 mol⋅kg⁻¹ were determined at temperatures of 298.15, 423.15, 473.15 and 523.15 K and pressures up to 28 MPa. The measurements were performed at ambient conditions using the commercial Picker differential flow calorimeter and at high temperatures and pressures with a customized Picker type calorimeter constructed at the Blaise Pascal University, Clermont-Ferrand. Standard molar heat capacities were obtained by weighted extrapolation to the infinite dilution limit. The contributions of –CO–, –O– and –OH groups to the standard molar volume and standard molar heat capacity were determined from the newly determined and literature data. The variation of the three oxygen-containing group contributions with temperature and molecular structure is examined qualitatively.     

Determination of Chemical Compounds and Investigation of Biological Properties of Matricaria chamomilla Essential Oils,Honey, and Their Mixture

This exploratory investigation aimed to determine the chemical composition and evaluate some biological properties, such as antioxidant, anti-inflammatory, antidiabetic, and antimicrobial activities, of Matricaria chamomilla L. essential oils (EOs). EOs of M. chamomilla were obtained by hydrodistillation and phytochemical screening was performed by gas chromatography–mass spectrophotometry (GC-MS). The antimicrobial activities were tested against different pathogenic strains of microorganisms by using disc diffusion assay, the minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) methods. The antidiabetic activity was performed in vitro using the enzyme inhibition test. The antioxidant activity of EOs was tested using the free radical scavenging ability (DPPH method), ferrous ion chelating (FIC) ability, and β-carotene bleaching assay. The anti-inflammatory effects were tested in vivo using the carrageenan-induced paw edema method and in vitro using the inhibition of the lipoxygenase test. The analysis of the phytochemical composition by GC-MS revealed that camphor (16.42%) was the major compound of EOs, followed by 3-carene (9.95%), β-myrcene (8.01%), and chamazulene (6.54%). MCEO, honey, and their mixture exhibited antioxidant activity against the DPPH assay (IC₅₀ ranging from 533.89 ± 15.05 µg/mL to 1945.38 ± 12.71 µg/mL). The mixture exhibited the best radical scavenging activity, with an IC₅₀ of 533.89 ± 15.05 µg/mL. As antidiabetic effect, EO presented the best values against α-glucosidase (265.57 ± 0.03 μg/mL) and α-amylase (121.44 ± 0.05 μg/mL). The EOs and honey mixture at a dose of 100 mg/kg exhibited a high anti-inflammatory effect, with 63.75% edema inhibition after 3 h. The impact of EOs on the studied species showed an excellent antimicrobial (Staphylococcus aureus ATCC 29213 (22.97 ± 0.16 mm)), antifungal (Aspergillus niger (18.13 ± 0.18 mm)) and anti-yeast (Candida albicans (21.07 ± 0.24 mm) effect against all the tested strains. The results obtained indicate that the EOs of M. chamomilla could be a potential drug target against diabetes, inflammation and microbial infections; however, further investigations to assess their bioactive molecules individually and in combination are greatly required.     

Ornamental Plant Efficiency for Heavy Metals Phytoextraction from Contaminated Soils Amended with Organic Materials

Accumulation of heavy metals (HMs) by ornamental plants (OPs) from contaminated agriculture soils is a unique technique that can efficiently reduce the metal load in the food chain. Amaranthus tricolor L. has attractive characteristics acquiring a higher growth rate and large biomass when grown at heavy metal contaminated soils. Site-specific detailed information is not available on the use of A. tricolor plant in metal phytoremediation from the polluted sites. The study aimed to enhance the uptake of HMs (Pb, Zn, and Cu) via amending poultry litter extract (PLE), vinasse sugarcane (VSC), and humic acid (HA) as natural mobilized organic materials compared to ethylene diamine tetraacetic acid (EDTA), as a common mobilized chemical agent by A. tricolor plant. The studied soils collected from Helwan, El-Gabal El-Asfar (Cairo Governorate), Arab El-Madabeg (Assiut Governorate), Egypt, and study have been conducted under pot condition. Our results revealed all organic materials in all studied soils, except EDTA in EL-Gabal El-Asfar soil, significantly increased the dry weight of the A. tricolor plant compared to the control treatment. The uptake of Pb and Zn significantly (p > 0.05) increased due to applying all organic materials to the studied soils. HA application caused the highest uptake as shown in Pb concentration by more than 5 times in Helwan soil and EDTA by 65% in El-Gabal El-Asfar soil while VSC increased it by 110% in El-Madabeg soil. Also, an increase in Zn concentration due to EDTA application was 58, 42, and 56% for Helwan, El-Gabal El-Asfar, and El-Madabeg soil, respectively. In all studied soils, the application of organic materials increased the remediation factor (RF) than the control. El-Madabeg soil treated with vinasse sugarcane gave the highest RF values; 6.40, 3.26, and 4.02% for Pb, Zn, and Cu, respectively, than the control. Thus, we identified A. tricolor as a successful ornamental candidate that, along with organic mobilization amendments, most efficiently develop soil health, reduce metal toxicity, and recommend remediation of heavy metal-contaminated soils. Additionally, long-term application of organic mobilization amendments and continued growth of A. tricolor under field conditions could be recommended for future directions to confirm the results.     

Vibrational spectroscopic detection of H-bonded β- and γ-turns in cyclic peptides and glycopeptides

The conformation of N-glycoproteins and N-glycopeptides has been the subject of many spectroscopic studies over the past decades. However, except for some preliminary data, no detailed study on the vibrational spectroscopy of glycosylated peptides has been published until recently.

This paper reports FTIR spectroscopic properties in DMSO and TFE of the N-glycosylated cyclic peptides cyclo[Gly-Pro-Xxx(GlcNAc)-Gly-δ-Ava] 3a and 3b in comparison with data on the non-glycosylated parent peptides cyclo(Gly-Pro-Xxx-Gly-δ-Ava) 2a and 2b [a, Xxx = Asn; b, Xxx = Gln; δ-Ava = NH-(CH₂)₄-CO] and N-acetyl 2-acetamido-2-deoxy-β- -gluco pyranosylamine (GlcNAc-NHAc, 4). The assignment of amide I band frequencies to conformation is based on ROESY experiments and determination of the temperature coefficients in DMSO-d₆ solution. (For the synthesis and NMR characterization of 2a and 3a see Ref. [19].)

Cyclic peptides are expected to adopt folded (β- and/or γ-turn) conformations which may be fixed by intramolecular H-bonding(s). A comparison of the temperature coefficients of the NH protons and amide I band frequencies and intensities suggests that in DMSO there is no significant difference in the backbone conformation and H-bond system of the N-glycosylated models and their parent cyclic peptides. The common feature of the backbone conformation of models 2 and 3 is the predominance of a 1 ← 4 (C₁₀) H-bonded type II β-turn encompassing Pro-Xxx or Pro-Xxx(GlcNAc), respectively. The ROESY connectivities in the Asn(GlcNAc) model (3a) have not been found to reflect intramolecular H-bondings between the peptide and the sugar.

The unique feature of the FTIR spectra in DMSO of the cyclic models is the lack or weakness of low-frequency (< 1640 cm⁻¹) amide I component bands. In TFE the amide I region of the FTIR spectra shows an increased number of components below 1650 cm⁻¹ reflecting a mixture of open and H-bonded β- and γ-turn conformers.

Because of its destabilizing effect upon γ-turns and other weakly H-bonded structures, DMSO decreases the number of backbone conformers. DMSO also destroys side-chain-backbone H-bondings of type C₇, C₆ or C₈. Possible ‘glyco’ C₇ H-bondings in GlcNAc-NHAc (4) or in glycopeptides 3a and 3b cannot resist the effect of DMSO either.

The FTIR data in TFE of models 2–4 suggest that the acceptor amide group of strong C₇ H-bondings in peptides and glycopeptides absorbs at 1630 ± 5 cm⁻¹ and that of bifurcated H-bondings between 1600–1620 cm⁻¹.