Polymerization of cyclic monomers. VII. Synthesis and radical polymerization of 1,3‐bis[(1‐alkoxycarbonyl‐2‐vinylcyclopropane‐1‐yl)carboxy]benzenes

1,3‐Bis[(1‐alkoxycarbonyl‐2‐vinylcyclopropane‐1‐yl)carboxy]benzenes 1 [RO: CH₃O (a), C₂H₅O (b)] were synthesized by the esterification of the corresponding 1‐alkoxycarbonyl‐2‐vinylcyclopropane‐1‐carboxylic acids with resorcinol. The structure of the new vinylcyclopropanes was confirmed by elemental analysis and infrared (IR), ¹H nuclear magnetic resonance (¹H‐NMR), and ¹³C nuclear magnetic resonance (¹³C‐NMR) spectroscopy. The radical polymerization of difunctional 2‐vinyl‐cyclopropanes in bulk with 2,2′‐azoisobutyronitrile (AIBN) results in hard, transparent, crosslinked polymers. During the bulk polymerization of the crystalline bis[(1‐methoxycarbonyl‐2‐vinylcyclopropane‐1‐yl)carboxy]benzene 1a, an expansion in volume of about 1% took place. The radical solution polymerization of 1a resulted in a soluble polymer with pendant 2‐vinylcyclopropane groups. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 1775–1782, 1999     

Chemical analysis of volatiles emitted by Pinus svlvestris after induction by insect oviposition

Gas chromatography – mass spectrometry analyses of the headspace volatiles of Scots pine (Pinus sylvestris) induced by egg deposition of the sawfly Diprion pini were conducted. The odor blend of systemically oviposition-induced pine twigs, attractive for the eulophid egg parasitoid Chrysonotomyia ruforum, was compared to volatiles released by damaged pine twigs (control) that are not attractive for the parasitoid. The mechanical damage inflicted to the control twigs mimicked the damage by a sawfly female prior to egg deposition. The odor blend released by oviposition-induced pine twigs consisted of numerous mono- and sesquiterpenes, which all were also present in the headspace of the artificially damaged control twigs. A quantitative comparison of the volatiles from oviposition-induced twigs and controls revealed that only the amounts of (E)--farnesene were significantly higher in the volatile blend of the oviposition-induced twigs. Volatiles from pine twigs treated with jasmonic acid (JA) also attract the egg parasitoid. No qualitative differences were detected when comparing the composition of the headspace of JA-treated pine twigs with the volatile blend of untreated control twigs. JA-treated pine twigs released significantly higher amounts of (E)--farnesene. However, the JA treatment induced a significant increase of the amount of further terpenoid components. The release of terpenoids by pine after wounding, egg deposition, and JA treatment is discussed with special respect to (E)--farnesene.     

Investigation of the microstructure of alkali-activated cements by neutron scattering

Significant research has been devoted to understanding and modeling the neutron scattering behavior of Portland cement pastes. The present work examines the potential of neutron scattering to noninvasively evaluate the properties of alternative cementitious materials encountered in the field. To interpret the scattering of both alkali-activated and slag-cement systems, alternative models to those typically adopted for Portland cement pastes were considered. Investigation of alkali-activated and slag-cement coupons were conducted for different sample thickness (∼0.5, 1, 2, 4, 6, 8 and 12 mm) over a wide scattering vector (Q) range (0.0005<Q>0.03 nm⁻¹ and 0.04<Q>4 nm⁻¹) on both ultra (USANS) and conventional small-angle neutron scattering (SANS) spectrometers. This wide Q range allowed determination of the fractal properties of the microstructure as well as the radius of the main scattering particle in the material. An empirical correction for multiple scattering was made based on the Dexter-Beeman equation and demonstrated that for thicker sample widths the theory correlated reasonably well. Alkali-activated fly ash was found to have the largest R value while the OPC and slag mix exhibited the largest Guinier radius. This difference was attributed to variations in the extent of multiple scattering for the samples. Successful application of this model was limited to sample thickness ≥1 mm. A combined power law-Sabine expression was also utilized to successfully model the SANS data over a Q range of 0.04-4 nm⁻¹.     

7-(Dialkylamino)coumarin-4-yl]methyl-Caged Compounds as Ultrafast and Effective Long-Wavelength Phototriggers of 8-Bromo-Substituted Cyclic Nucleotides

[7-(Dimethylamino)coumarin-4-yl]methyl (DMACM) and [7-(diethylamino)coumarin-4-yl]methyl (DEACM) esters of 8-bromoadenosine 3',5'-cyclic monophosphate (8-Br-cAMP) and 8-bromoguanosine 3',5'-cyclic monophosphate (8-Br-cGMP) are described as novel caged compounds for 8-bromo-substituted cyclic nucleotides. Synthesis is accomplished by treatment of the free acids of the cyclic nucleotides with the corresponding 7(dialkylamino)-substituted 4(diazomethyl)coumarins. Irradiation of the DMACM- and DEACM-caged cyclic nucleotides with UV light stimulates the release of the cyclic nucleotides within roughly a nanosecond. The new caged compounds are resistant to hydrolysis in aqueous buffers and exhibit long-wavelength absorption properties with maxima at 400 nm, high extinction coefficients, and high quantum yields (0.15-0.31). Their favorable properties render these compounds the most efficient and rapid phototriggers of 8-bromo-substituted cyclic nucleotides known. The usefulness of the compounds for physiological studies under nondamaging light conditions was examined in HEK293 cells expressing the alpha subunit of the cyclic-nucleotide-gated (CNG) channel of cone photoreceptors (CNGA3) and of olfactory neurons (CNGA2) by using confocal laser scanning microscopy and the patch clamp technique.     

ACHEMA 2022: Membranes and Membrane Processes

Numerous companies working in the field of membrane development, membrane production, and membrane separation engineering were present at ACHEMA 2022. Compared to the last ACHEMA in 2018, there were fewer attending companies and only few new topics since development has been blocked partially by the pandemic situation and the subsequent restrictions of this years. Nevertheless, some new developments have been identified concerning process design as well as ceramic and polymeric systems.     

Entwicklung einer kontinuierlichen Mikrowellen‐Vakuumtrocknungsanlage mit hexagonalem Verfahrensraum

A continuous microwave vacuum drying processor with a hexagonal cross‐section of the cavity was constructed. Due to the geometry of the cavity and the continuous movement of the product, homogeneous microwave power absorption of the product can be favored. By the expansion and simultaneous dehydration of non‐expanded, starch‐based extrudates, the applicability of the constructed processor could be shown.     

Identification of New N‐Acylhomoserine Lactone Signalling Compounds of Dinoroseobacter shibae DFL‐12T by Overexpression of luxI Genes

Bacteria of the Roseobacter clade are widespread in the ocean and occur in many different habitats. In the genome of Dinoroseobacter shibae DFL‐12, luxI homologous genes that encode synthases responsible for the formation of N‐acylhomoserine lactones (AHLs) have been described. These compounds are known autoinducers that regulate several biological traits—namely, flagella formation and cell differentiation—in D. shibae through quorum sensing. The AHLs produced by D. shibae mainly consisted of N‐octadecadienoylhomoserine lactone (C18:2‐AHL) and N‐octadecenoylhomoserine lactone (C18:1‐HSL). In the wild type these AHLs are synthesized only in low abundance. The luxI genes were therefore expressed in Escherichia coli; this resulted in the formation of AHLs mostly different from those found in the D. shibae wild type. A luxI₁‐deficient mutant of D. shibae was then reprovided with an overexpressed luxI₁ gene. This strain produced large amounts of C18:2‐AHL and C18:1‐AHL, allowing full characterization of these compounds by mass spectrometric techniques and derivatization. Synthesis of the proposed structures confirmed that the major compound is (2E,11Z)‐N‐octadeca‐2,11‐dienoylhomoserine lactone ( 6 , C18:2‐HSL), accompanied by (Z)‐N‐octadec‐11‐enoylhomoserine lactone ( 5 , C18:1‐HSL). AHL 6 has not been reported before from other organisms and contains an unusual 2E double bond.     

Modification of Polycarbonate and Glycol Modified Poly(ethylene terephthalate) by Addition of Silica‐Nanoparticles Grafted with SAN Copolymer Using “Classical” and ARGET ATRP

This study presents a nanocomposite manufacturing route starting from non‐functionalized nanosilica and SAN surface modification via “grafting from” ATRP up to processing of transparent polycarbonate and glycol modified poly(ethylene terephthalate) nanocomposites. Synthesis limitations of low molecular weight graft SAN derived from “classical” ATRP are overcome by employment of the emerging ARGET ATRP. Mechanical investigations of polycarbonate and glycol modified poly(ethylene terephthalate) nanocomposites present up to 80% enhancement of creep performance and additionally 70% enhancement against wear abrasion for glycol modified poly(ethylene terephthalate) nanocomposites. Strength and tensile modulus are only moderately influenced by the addition of nanoparticles. Morphological studies confirm that the present modification route is able to create uniform dispersions of single particles and small particle aggregates in polymer matrices.